My own illiteracy! LMAO

I just started using Ret Hat 7.2
I don't understand how you would go about downloading Java from an online tree... it confuses me. I'm learning.. but not fast enough... and I can't get the LimeWireLinux.bin file to open at all.

My computer Auto-loads to a KDE Graphical interface becuase of something my roommate did... and when you try to run an RPM file it asks you for the root pw.... beyond running an RPM file I don't know how to do crap.

If somebody would please explain to me, in easy steps made for a six year old, it would be much appreciated.