The vehicle must be OFF. 
Place the replacement key fob in the console pocket with the buttons facing forward. 
Insert the vehicle key in the driver door lock cylinder located in the driver door handle and cycle the key 5 times within 5 seconds. 

The DIC will display a message: OFF/ACC TO LEARN. 
Press the OFF/ACC portion of the ignition button. 
The DIC will display a message: WAIT 10 MINUTES, then it will count down from 10 to 0, one minute at a time. 
When the counter reaches 0, DIC will display OFF/ACC TO LEARN. 
Repeat steps 5-7 two more times, for a total of 30 minutes. 
The DIC will display a message: OFF/ACC TO LEARN. 
Press the OFF/ACC portion of the ignition button. 
A beep will occur and the DIC will display: READY FOR FOB 1. At this time all previously known key fobs have been erased. When fob 1 is programmed a beep will be heard and the DIC will display a message: READY FOR FOB 2. 
Additional key fobs can be programmed by taking fob 1 out of the pocket and inserting fob 2. If desired, up to 4 fobs can be programmed. Once 4 fobs have been learned, the DIC will display a message: MAX FOBS LEARNED, and automatically exit the program mode. 
If learning less than 4 key fobs, press the OFF/ACC portion of the ignition button to exit the program mode. 
Operate the active portion of each key fob in order to finalize the programming sequence and verify correct system operation    I take no credit for this is a copy and paste from the web  i cant spell that well.