How do I program a new key fob for my GM car?

gm dealer

depends on the car, if it's less than maybe 2 or 3 years old go on the dic and select learn remote key and it walks you through. then there are some that you sit in the car and while holding the power door unlock button turn the key on and off.. can't remember if it's 3 or 5 times, you'll hear a horn chirp, then hold lock and unlock on the remote until the locks cycle, you have to hold lock and unlock for every remote because when it comes out of programming mode only the remotes programmed in that session will work, after you've prgrammed all your remotes turn the key off and the horn will chirp again and it's out of mode. that works for some cars, if it doesn't you need a tech 2