This
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
StartToolStripMenuItem.PerformClick()
End Sub
Or This
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
StartToolStripMenuItem_Click(StartToolStripMenuItem, EventArgs.Empty)
End Sub