Silkroad Online SENDKEYS API

[ZuOo]

Hello.
I want make simple clicker on vSRO.
but I can't do so would only click on SRO
I know I need to use SendMessage API but I do not know how to do it
Can someone show me it on this code:

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Timer1.Start()

    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        SendKeys.Send("1")

    End Sub
End Class

I found SendMessage API tut but I don't understand it :
[VB.NET] SendMessage Tutorial
please help me