Calculadora del area de un circulo

Sacamos el area de un circulo con los siguientes datos:
   Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        End
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim numero As Double
        numero = TextBox1.Text
        TextBox2.Text = numero * numero * 3.1416
    End Sub
End Class

 Se pusieron tres label,dos buttms