This is almost impossible to answer without know exactly what you are doing (or doing wrong), as well as the manufacturer of your garage door opener.
I'm assuming that you have a rolling-code garage door opener. In which case it's a two step process:
- 1st Step is to train the desired HomeLink button to recognize the garage door opener. This is done with with your hand held garage remote.
- 2nd Step is to sync the newly trained HomeLink button to the opener's rolling code. This is done by hitting the proper button on your ceiling mounted garage door opener, and within 30 seconds, press and holding the desired Homelink button until the light on the garage door opener blinks once (or twice).
Maybe watching a YouTube video may help. In any event, carefully follow the steps in your Accord owner's manual for the type of garage door opener (rolling-code or non rolling-code). Also, check the user's manual that came with your garage door opener.
This is the best that I can come up with. Good luck!