The screen of death. Instructions on reloading OS anywhere?

Howdy, Folks!

I bet you've missed me and my elementary questions regarding computer issues, eh? :>)

I recently was given a new-to-me tower/PC with XP on it (since my WIN2K no longer works with so many browsers and my new printer, dagnabbit!). Unfortunately after a week or so I got an error message on it, "Disk Boot Failure, Insert System Disk and Press Enter".

I rec'd an XP CD last week, put it in the computer but ended up getting so many choices to click on I have no idea how to load it all up again.

Question: Is there a dummied down site that will lead me to reloading this OS in a step by step manner?

As for now I'm still using my Win2K computer so am able to get online but sure would like to get a newer-improved OS so I can access other browsers beside Opera and also use a new printer I have. I was glad I hadn't started using the XP tower full time nor have I moved my files over to it yet, which will be yet another piece of education because I only know how to put files on a flash drive then plug the flash drive in to the new(er) computer and copy over; yikes, lots of copying there, eh?)

Any guidance, words of encouragement or commiseration is greatly appreciated.

Shoe