How do you program remote garage door button in a 2004 Chevy Avalanche to open garage door?

To program the remote garage door button in a 2004 Chevy Avalanche, first, ensure the vehicle is parked and the ignition is in the "On" position. Then, press and hold the two outer buttons on the HomeLink system until the indicator light changes from a slow blink to a rapid blink. Next, hold the garage door remote close to the HomeLink buttons and simultaneously press the button on the remote and the desired HomeLink button until the light blinks and then turns solid. Finally, test the programmed button to ensure it operates the garage door.