Re-naming class from a new runescape jar file

How do I do that. I got a 530 runescape jar file. Extracted it, decompiled it, still have to fix some errors. But there all names like a.class file, aa.class file etc. How do I change them? What server should I use for this client?

Thanks

Deobfuscate it.

Thanks for the help Stewie. Now I just need an answer for the last question.