Here is the diagram for the 2002 Pontiac Firebird with the 6 cylinder engine as requested in the forum.
To remove the belt, rotate the tensioner pulley creating slack in the belt and slip it off the pulleys.
Check all the pulleys and make sure they are free of any debris, fluids and make sure they are not damaged in any way.
To install the belt, select the correct diagram for your vehicle (with or without AC). Route the belt around all of the pulleys leaving the tensioner pulley for last. After you have routed the belt according to the diagram, rotate the tensioner pulley just enough to slip the belt over it.
Double check the routing and make the belt is on every pulley correctly before starting your vehicle.
If you are not using the AC the belt will be shorter. It would be a good idea to take your old belt with you to the auto parts store tomake sure getting the correct one. This diagram was requested in the discussion forums and some info was requested about removing the AC. If your vehicle is already with the AC compressor you can just buy the proper belt. If you need to remove the AC you can use the smaller belt or you can find a bypass pulley that goes where your AC at your local auto parts store.