Need Api ASAP

I need an api to distinguish between right and left clicking of the mouse. I want to have right click menus but i am unable to have the program distinguish whether the user clicked using the left button or the right.

Any help would be appreciated.

Optic

Code:

---

Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)

    If Button = vbRightButton Then
        Msgbox "Button 2 clicked"
    End If

End Sub

---