it's in the manual, but here's the basic steps:
1. press the two outer button together for few seconds until the light flashes.
2. take your remote garage door opener near the rear view mirros. Press the remote button and the desired button on the mirror together. Wait for a few seconds until the light blinks rapidly.
3. go to the garage door motor and press the "learn" button.
4. quickly come back to your car and press the button on the mirror that you just programmed.

that should activate the garage door. Good luck

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2011 BMW 740i
2011 Toyota Sienna Limited
2008 X5 3.0 Space Gray (sold)