For your iBook G4, I would suggest that you look at a book that shows information up to OS X 10.5 (Leopard)
Keep in mind that model will be AT LEAST 8 years old, is very challenging to repair, and is dramatically different hardware, compared to that on more current models.
The OS X software, however, will look and work the same on any Mac of that vintage, depending on the OS X version in use.
Keep in mind that the iBook will limit you somewhat with how much RAM memory can be used, as there's only one memory slot.