Leg #4 is your common.
so whatever you are going to connect to it, will close a circuit with leg # 1 when pressing one side of the switch, and with leg # 2 when pressing the other side.
if you connect both legs together as shown, the garage door will open no matter which side of the switch you press.
this is all assuming you have the type of remote that has the same button for closing and opening.
if you have 2 buttons, well.... i'll have to make another drawing
