Sounds like a really old PBG4 if it's running OS9.2.2.
To help you determine how far you can upgrade the OS, we need the "machine model" or "model identfier code." By default, OS9 has "Apple System Profiler" in the Apple menu. Launch it.
On the first page that comes up is a lot of tech info on the computer that includes the mode codel. However, if you've not opened ASP before, the info may be in collapsed sections. Click the little disclosure arrows until you find a code that is in the format "PowerBook3,2" (the numbers vary with the model--that's the key to identifying).
The MacTracker database shows that only the first G4 PowerBook, the "3,2" version in my example, shipped with OS9 only. From the next model on, they shipped with some version of OSX. The same database says the 3,2 will support up to Mac OSX "Tiger" (OS 10.4.11) but you'll like need ot max out your RAM to 1G if it's not already there.
The Airport card issue could be security encryption level If you are trying to connect to a modern router with WPA or higher encryption. That's probably too high for your model PB. Try dialing down the router's encryption level to WEP and see if the Airport starts working.