The project today is Screen lock, Screen lock is used to lock the screen of your computer. and not just to access or tamper with your work. yet you will be able to access that requiring the user to perform a certain action in order to receive access, like log-in or click the button. here are one example of the lock screen.

First open Microsoft Visual Studio 2008/2010 and Create New Project and name it and then add three Form, first form the main form, second the background or the block screen and third form the close or unblock form. Then add  three Module. first Lock Screen Module, second Lock System Parameters and Native module.

Lock Screen Module
Imports System.Threading
Public NotInheritable Class LockScreen
    Private myForm As Form
#Region " System Locking Methods "

    Public Function LockSystemAndShow(ByVal myDForm As Form) As Boolean
        myForm = myDForm


        Dim scr As Screen

        scr = Screen.PrimaryScreen

        Dim background As Bitmap = New Bitmap(scr.Bounds.Width, scr.Bounds.Height)
        Using g As Graphics = Graphics.FromImage(background)

            g.CopyFromScreen(0, 0, 0, 0, scr.Bounds.Size)
            Using br As Brush = New SolidBrush(Color.FromArgb(192, Color.Black))
                g.FillRectangle(br, scr.Bounds)
            End Using



        End Using

        Dim originalThread As IntPtr
        Dim originalInput As IntPtr
        Dim newDesktop As IntPtr

        originalThread = GetThreadDesktop(Thread.CurrentThread.ManagedThreadId)
        originalInput = OpenInputDesktop(0, False, DESKTOP_SWITCHDESKTOP)

        newDesktop = CreateDesktop("Desktop" & Guid.NewGuid().ToString(), Nothing, Nothing, 0, GENERIC_ALL, Nothing)
        SetThreadDesktop(newDesktop)
        SwitchDesktop(newDesktop)

        Dim newThread As Thread = New Thread(AddressOf NewThreadMethod)
        newThread.CurrentCulture = Thread.CurrentThread.CurrentCulture
        newThread.CurrentUICulture = Thread.CurrentThread.CurrentUICulture
        newThread.Start(New LockSystemParameters(newDesktop, background))
        newThread.Join()

        SwitchDesktop(originalInput)
        SetThreadDesktop(originalThread)

        CloseDesktop(newDesktop)
        CloseDesktop(originalInput)

        Return True

    End Function

    Private Sub NewThreadMethod(ByVal params As Object)
        Dim v As LockSystemParameters = DirectCast(params, LockSystemParameters)
        SetThreadDesktop(v.NewDesktop)
        Using f As Form = New BlockScreen(v.Background)
            f.Show()
            myForm.ShowDialog()
            f.BackgroundImage = Nothing
            Application.DoEvents()
            Thread.Sleep(250)
        End Using
    End Sub

#End Region
End Class

Lock System Parameters
Friend Class LockSystemParameters
    Public NewDesktop As IntPtr
    Public Background As Bitmap
    Public Sub New(ByVal newDesktop As IntPtr, ByVal background As Bitmap)
        Me.NewDesktop = newDesktop
        Me.Background = background
    End Sub
End Class

 Native module
Imports System.Runtime.InteropServices

 _
Friend Module Native

    Public Const GENERIC_ALL As Integer = &H10000000
    Public Const DESKTOP_SWITCHDESKTOP As Integer = &H100L

    Public Declare Auto Function GetThreadDesktop Lib "user32.dll" (ByVal threadId As Integer) As IntPtr
    Public Declare Auto Function OpenInputDesktop Lib "user32.dll" (ByVal flags As Integer,  ByVal inherit As Boolean, ByVal desiredAccess As Integer) As IntPtr
    Public Declare Auto Function CreateDesktop Lib "user32.dll" (ByVal desktop As String, ByVal device As String, ByVal devmode As IntPtr, ByVal flags As Integer, ByVal desiredAccess As Integer, ByVal lpsa As IntPtr) As IntPtr
    Public Declare Auto Function SetThreadDesktop Lib "user32.dll" (ByVal desktop As IntPtr) As  Boolean
    Public Declare Auto Function SwitchDesktop Lib "user32.dll" (ByVal desktop As IntPtr) As  Boolean
    Public Declare Auto Function CloseDesktop Lib "user32.dll" (ByVal desktop As IntPtr) As  Boolean

End Module

In main form there have a 2 button The LOCK and EXIT.
Public Class MainForm

    Private Sub MainForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.Location = New Point(10, 10)
    End Sub

    Private Sub btnlock_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnlock.Click
        Dim myObj As LockScreen = New LockScreen
        myObj.LockSystemAndShow(CloseBotton)
    End Sub

    Private Sub btnexit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnexit.Click
        End
    End Sub

End Class

The background or the block screen.
Public Class BlockScreen
    Inherits Form

    Private background As Bitmap

    Public Sub New(ByVal background As Bitmap)
        Me.BackColor = Color.Black
        Me.FormBorderStyle = FormBorderStyle.None
        Me.Location = Point.Empty
        Me.Size = Screen.PrimaryScreen.Bounds.Size
        Me.StartPosition = FormStartPosition.Manual
        Me.Visible = True
        Me.background = background
    End Sub

    Protected Overrides Sub OnShown(ByVal e As System.EventArgs)
        Me.BackgroundImage = background
        Me.DoubleBuffered = True
        MyBase.OnShown(e)
    End Sub
End Class


The Close or Unblock form
Public Class CloseBotton

    Private Sub btnunlock_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnunlock.Click
        Me.Close()
    End Sub

    Private Sub CloseBotton_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.Location = New Point(10, 10)
    End Sub
End Class

Follow the code and you... create your own lock screen with login.
If you want the copy of this project. Here's the link.  
http://j.gs/6IHD

This Project Design and Program By: lyo
The Project For today is how to make Calculator in VB.net. Look the Image above that is the design of our Calculator.

First Step: Open your Microsoft Visual Studio 2008/2010 and create new project and name your  project.

Second Step: In your Form1 add one(1) textbox and twenty six(26) button to your form

Form1 = FormCalculator
TextBox1 = txtscr
Button1 = btnmc - MC
Button2 = btnmr - MR
Button3 = btnms - MS
Button4 = btnmad - M+
Button5 = btnbps - <
Button6 = btnclr - C
Button7 = btnpn - ±
Button8 = btnsqu - √
Button9 = btn1 - 1
Button10 = btn2 - 2
Button11 =  btn3 -3
Button12 = btn4 - 4
Button13 = btn5 - 5
Button14 = btn6 - 6
Button15 = btn7 - 7
Button16 = btn8 - 8
Button17 = btn9 - 9
Button18 =btn0 - 0
Button19 =btndot - .
Button20 = btnadd - +
Button21 = btnsub - -
Button22 = btnmul - *
Button23 = btndiv - /
Button24 = btnper - %
Button25 = btnint - ¹/แตก
Button26 = btnequ - =

Add this piece of code after Public Class FormCalculator
    Dim Value1 As Double
    Dim Value2 As Double
    Dim tempMemory As Double
    Dim tempMem As Double
    Dim tempOperation As String
    Dim hasDecimal As Boolean
    Dim tempValue As Double 

Like This:
    Public Class FormCalculator

    Dim Value1 As Double
    Dim Value2 As Double
    Dim tempMemory As Double
    Dim tempMem As Double
    Dim tempOperation As String
    Dim hasDecimal As Boolean
    Dim tempValue As Double


 Then lets code Button:

(MC) Button. This button means Memory Clear
Private Sub btnmc_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnmc.Click
        tempMemory = vbNullString
    End Sub

(MR) Button. Memory Recall
 Private Sub btnmr_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnmr.Click
        If tempMemory <> "0" Then
            txtscr.Text = tempMemory
        End If
    End Sub

(MS) Button. Memory Stores
    Private Sub btnms_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnms.Click
        If txtscr.Text.Length >= 1 Then
            tempMemory = txtscr.Text
        End If
    End Sub

(M+)Button. Add to Memory
Private Sub btnmad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnmad.Click
        If tempMemory <> "0" Then
            tempMem = tempMemory + txtscr.Text
            txtscr.Text = tempMem.ToString()
            tempMemory = txtscr.Text
        End If
    End Sub

(<)Button. BackSpace
Private Sub btnbps_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnbps.Click
        Dim tempSting As String
        Dim tempInteger As Integer
        If txtscr.Text.Length > 0 Then
            tempSting = txtscr.Text.Chars(txtscr.Text.Length - 1)
            If tempSting = "." Then
            End If
            tempInteger = txtscr.Text.Length
            txtscr.Text = txtscr.Text.Remove(tempInteger - 1, 1)
        End If
    End Sub

(C)Button. Clear All
 Private Sub btnclr_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnclr.Click
        txtscr.Text = vbNullString
    End Sub

(±)Button. Positive and Negative Symbols
Private Sub btnpn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnpn.Click
        txtscr.Text = -1 * txtscr.Text
    End Sub

(√)Button. Square Root
Private Sub btnsqu_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnsqu.Click
        If txtscr.Text.Length <> 0 Then
            TempValue = CType(txtscr.Text, Double)
            TempValue = System.Math.Sqrt(TempValue)
            txtscr.Text = CType(TempValue, String)
            hasDecimal = False
        End If
    End Sub

(1-9)Button. Number1 to 9 put this code only to Button Code
  txtscr.Text = txtscr.Text & sender.Text

(0)Button. Number0
 Private Sub btn0_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn0.Click
        If txtscr.Text.Length >= 1 Then
            txtscr.Text = txtscr.Text & sender.Text
        End If
    End Sub

(.)Button. Decimal Point
Private Sub btndot_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btndot.Click
        If InStr(txtscr.Text, ".") > 0 Then
            Exit Sub
        Else
            If txtscr.Text.Length >= 1 Then
                txtscr.Text = txtscr.Text & sender.text
            Else
                txtscr.Text = txtscr.Text & btn0.Text + sender.text
            End If
        End If
    End Sub

(+)(-)(*)(/)Operation Button.
Private Sub btnadd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnadd.Click
        Value1 = Val(txtscr.Text)
        txtscr.Text = ""
        txtscr.Focus()
        tempOperation = "+"
    End Sub

    Private Sub btndiv_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btndiv.Click
        Value1 = Val(txtscr.Text)
        txtscr.Text = ""
        txtscr.Focus()
        tempOperation = "/"
    End Sub

    Private Sub btnmul_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnmul.Click
        Value1 = Val(txtscr.Text)
        txtscr.Text = ""
        txtscr.Focus()
        tempOperation = "*"
    End Sub

    Private Sub btnsub_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnsub.Click
        Value1 = Val(txtscr.Text)
        txtscr.Text = ""
        txtscr.Focus()
        tempOperation = "-"
    End Sub


(%)Button.
Private Sub btnper_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnper.Click
        Dim tempResult As Double
        Value2 = Val(txtscr.Text)
        Select Case tempOperation
            Case "+"
                tempResult = (Value1 + Value2) * (1 / 100)
                txtscr.Text = tempResult.ToString()
            Case "-"
                tempResult = (Value1 - Value2) * (1 / 100)
                txtscr.Text = tempResult.ToString()
            Case "/"
                tempResult = (Value1 / Value2) * (1 / 100)
                txtscr.Text = tempResult.ToString()
            Case "*"
                tempResult = (Value1 * Value2) * (1 / 100)
                txtscr.Text = tempResult.ToString()
        End Select
        txtscr.Text = tempResult.ToString()
    End Sub

(¹/แตก)Button.
Private Sub btnint_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnint.Click
        Dim convert As Single
        If txtscr.Text <> 0 Then
            convert = 1 / Val(txtscr.Text)
            txtscr.Text = convert
        End If
    End Sub

(=)Button.
Dim tempResult As Double
        Value2 = Val(txtscr.Text)
        Select Case tempOperation
            Case "+"
                tempResult = Value1 + Value2
                txtscr.Text = tempResult.ToString()
            Case "-"
                tempResult = Value1 - Value2
                txtscr.Text = tempResult.ToString()
            Case "/"
                tempResult = Value1 / Value2
                txtscr.Text = tempResult.ToString()
            Case "*"
                tempResult = Value1 * Value2
                txtscr.Text = tempResult.ToString()
        End Select
        txtscr.Text = tempResult.ToString()
    End Sub

Now that should be it, you have a very simple Calculator in vb.net.
If you want the copy of this project. Here's the link.  
http://adf.ly/1LwCkd

This Project Design and Program By: lyo