Dim Help As New Form
 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
        Help.Close()
        Help = New Form2
        Help.Show()
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button2.Click
        Help.Close()
        Help = New Form3
        Help.Show()
    End Sub