Well, for sure you should get an owners manual. Try doing an advanced search of this forum for "homelink". The instructions have been posted countless times including by me.
I had problems when I first programmed the botton for my garage opener, mine is rolling code one. After several attempts of going up and down, I realized, to program a rolling code garage door opener, you need to have you remote control that came with the opener. Press the learn button on your garage door opener unit, press the remote control while holding one of the three homelink buttons, then wait until the light go flashing from steady. Then go press the learn button again and press/hold the homelink button for a couple seconds TWICE, then it will work, at least for me. The manual does not state you need to use your remote control prior to pressing the homelink buttons twice. Hope this helps. thanks.