Hi,
Those three little buttons on the rear view mirror are for your "garage door opener." Instead of clipping that big remote to your visor, you can program those buttons to open your gearge for you. Didn't the sales person give you a walk-through of your car?
I haven't programed mine yet, but from what I was told, it's pretty easy to do. (I haven't read the manual yet, but let's be honest, I'm a man and appearantly have no desire to do so. Unless there is a secret code hidden in there that will unleash an additional 3oo horse into the car! Hey, I can dream!!)
Hope this helps!