How do I format my computer using the Windows XP CD?

I want to go to format my computer and erase everything and start from scratch … I have the window XP CD and the code but none of the options deleted my files. When I said that you should give me an option to delete my partitioned space but dosent .. I do not know what I have computer. iBUYPOWER it just says on the cover of the computer .. please help! when he gives the option to boot from cd i do it, but dosent give me an option .. it will create, then download, update, cancel

Boot from the CD and there should be an option to format the hard b4 installing, unless the boot disk not OG.