Depending on the make and model opener you have the learn button could be either Switches, Green, Orange, Purple or Yellow.
The button is on your opener right above the antenna wire. That wire hangs above the motor head. Some models have the button located on the back of the unit. Others are located on the side. If you have a light on the back of your opener, the button will be underneath the light cover.
Click Below On The Color Of Your Learn Button To Locate Available Receiver Logic Boards.