Pontiac Repair: Gear Shift, safety switch, electrical problem

Question
I own a 1998 Grand Prix. I start the car and everything is fine. When I try to shift from Park to Drive, the button that you press in to shift the gearstick back does not work--it is locked in place. I know this is most likely a safety feature or an electrical problem, so if possible, a hint on how to fix this and whether i can do it myself or not would be greatly appreciated!

Answer
It could be the safety switch for the brake pedal.
Do you usually have to press the brake to shift into drive?
Or is there a sticker that says you have to depress brake?

Test your brake lights (press the pedal and have someone look at the brake lights).
It could be in the shift handle itself, but i suspect the safety switch.
Ask again with the answers.