help me

I use Access DB in this cood what i want it to use SQL server (DB)  what i can do to change this cood ????? and also what i can write in Web.config.??

Public Class login

Inherits System.Web.UI.Page

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.

<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

End Sub

Protected WithEvents Label1 As System.Web.UI.WebControls.Label

Protected WithEvents Label2 As System.Web.UI.WebControls.Label

Protected WithEvents Label3 As System.Web.UI.WebControls.Label

Protected WithEvents TextBox1 As System.Web.UI.WebControls.TextBox

Protected WithEvents TextBox2 As System.Web.UI.WebControls.TextBox

Protected WithEvents Button1 As System.Web.UI.WebControls.Button

Protected WithEvents RequiredFieldValidator1 As System.Web.UI.WebControls.RequiredFieldValidator

Protected WithEvents RequiredFieldValidator2 As System.Web.UI.WebControls.RequiredFieldValidator

'NOTE: The following placeholder declaration is required by the Web Form Designer.

'Do not delete or move it.

Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init

'CODEGEN: This method call is required by the Web Form Designer

'Do not modify it using the code editor.

End Sub

#End Region

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

'Put user code to initialize the page here

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim cn As New OleDb.OleDbConnection

Dim cm As New OleDb.OleDbCommand

Dim dr As OleDb.OleDbDataReader

Dim username As String = TextBox1.Text

Dim password As String = TextBox2.Text

' Try

' open connection here

cn.ConnectionString = ConfigurationSettings.AppSettings("ConnectionString")

cm.CommandText = "Select * From Users Where Username='" & username _

& "' AND Password='" & password & "'"

If dr.HasRows Then

Session("LoginOk") = True

Response.Redirect("index.aspx")

Else

Label1.Text = "Invalid username or password"

End If

' Catch ex As Exception

' Label1.Text = ex.Message

' End Try

End Sub

End Class