If you want to process the click event on a button, then you should proceed on that by right click the button and adding an event handler (i.e. click). I can't remember it properly, but I think that if you double click the button the event handler is automatically created for you...
If you want to control the mouse buttons, then you can filter the messages
WM_LBUTTONDOWN[
^],WM_RBUTTONDOWN...
Hope this helps.
Good luck.