I currently own an iMac G4 that I bought from someone online. But now that I try to update it, it won't let me. The Safari doesn't work and I really just want to clean it up and really start from fresh.
You need to contact the seller and see if they have the original OS install discs, as they'll have iLife and a correct version of OS X. Barring that, try to get ahold of a set of retail OS install discs for anywhere from 10.3 (Panther) to 10.5 (Leopard). I'd suggest you get the newest your system will support. (It's important to look for retail discs so you don't have to spend extra energy trying to match your Mac's exact specs and model with the one the discs were shipped with.)
How to choose which disc to get if you can find multiple OS versions?