ASP.NET doesn't provide a built-in method for giving a control the input focus when the page loads. In fact, you can assign the TabIndex properties to controls on a page, but you can't use this property to set the initial focus on a control of your choice.
The following procedure provides you with the ability to do exactly this
Sub SetControlFocus(ByVal ctrl As Control)
Private Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles _
SetControlFocus( TextBox2 )