G4 Mac Hard Drive Issue?

I have a G4 my dad gave me... he used it since it came out for music production. As soon as the G5 came out he jumped on it and had an extra computer. It sat around for a year or two. Then I came upon it. I turned it on and it was running an older operating system. I bought OSX but when i try to install the os it crashes. I think it's the hard drive. It clicks seems like it's struggling to install. I got rid of the old os and now I have no system to run. No matter what i do It freezes or doesnt load. I have 3 hds The internal and then two additional ones. I'm stuck... I need help. I don't know if I should bring it in to a shop or how much it would cost to get fixed. Any suggestions are welcome.

If you have extra hard drives, pop one in and see if you can get that to work. Clicking is usually a good sign of hard drive failure.

How much RAM do you have?