You will need a tech 2 to program your remotes here is the procedure
Transmitter Programming
Important: All transmitters which are to be recognized by the remote control door lock receiver (RCDLR) must be programmed in a single programming sequence. If the system is placed in program mode it will erase all previously programmed transmitters upon the receipt of the programming signal from the first transmitter. Up to 4 transmitters can be programmed. Do not operate or program the transmitters in the vicinity of other vehicles that are in the keyless entry program mode. This prevents the programming of the transmitters to the incorrect vehicle.
Install a scan tool. (tech 2)
Use the scan tool in order to access programming: Vehicle Control System/Computer Integrating System/Module Setup/BCM/Program Key Fobs.
Press the START soft key on the scan tool.
Important: The scan tool must stay connected until all of the transmitters are programmed.
Press and hold the LOCK button and the UNLOCK button simultaneously on one transmitter. After a delay of 5-10 seconds, the scan tool will indicate that the transmitter is programmed.
Repeat the previous step in order to program up to 4 transmitters.
Remove the scan tool.
Operate the transmitter functions in order to verify correct system operation.