To be certain, I recommend:
* Consulting your owner's manual: This will have a diagram showing the location of the PCV valve.
* Using a repair manual (like a Haynes or Chilton): These manuals usually have detailed diagrams and instructions.
* Searching online for a diagram specific to your year and engine: A Google image search for "1997 Pontiac Firebird 3800 V6 PCV valve location" might yield helpful images.
Remember to be careful when working around the engine compartment. The engine and components can be hot, even after the car has been off for a while.