Hello, great that you want to learn more!
Sadly, PowerBooks and other PPC Macs have basically been abandoned by Apple & 95% of Software writers.
The last really supported Flash for PPC was 10.1.102.64, but if it's for like Facebook or such, people have been fooling FB to think they have a later version installed.
Texas Mac Man's Flash hack/post...
Flash player 11.1 hack on PowerPC -
See in each Browser which version of Flash it thinks it has...