help!

 I've read all I could fine about formatting my hard drive on my Demension 4300. I've read that I need to make my CD-Rom my first boot sequence, did that, don't  work.  Downloaded bootable files from MS to floppys, they work, but still not formatting. Running XP have both upgrade and full XP disks. I know someone is going need more info. from me, but don't know what.

                                                        Please Help Gene