I'll add:
1. This could take as long as 30 seconds before the door moves when programming.
2. DO NOT repeatedly press the "learn" button on the genie motor without attempting to program a remote or letting enough time pass for the LED to stop flashing before pressing it again. Pressing it too many times in short period will erase ALL remotes from the motor (I did this at my dad's house by accident, so I got his car programmed but all other remotes tied to this opener were deleted and had to be re-programmed.
3. This one should be obvious: DO NOT park the vehicle under the door while programming (be completely in or out of the garage when programming).