OBD-II equipped contours (96+) can ONLY be read with a scanner, or the like. There is no "built in" method, like for OBD-I cars.
Go to Autozone, tell them your CEL is on, and they will scan it for free.
Get the actual CODE that your car has triggered, and not the stupid explanation the parts guy tries to give you. the NUMBER CODE. bring it back here, and post it to get a push in the right direction.