You aren't providing enough information for anyone to help you. Please
answer the previous questions in full.

Rodgie, to begin with Why do yuo need to uninstall XP 'before' you can
re-install it again? If you PC came with recovery disks the recovery disk
will simply overwrite all that is on yuor hard drive and your pc will be
restored back to factory conditions. This also applies if the backup copy of
xp has been installed on an hidden partition by your pc manufacturer. I
suggest you first read your PCs user manual to find out what the procedure
is for re-installing the system.

You say that the CD does not run when you hit the power? Are we talking
about recovery CDs or a retail copy of Windows XP. If they are recovery
disks how many are there? In most cases recovery disks are numbered 1,2,3
etc. Insert disk 1 (one) into the CD drive and a menu should appear. You
just need to select the option to re-install the operating system and then,
as the system asks for the next disk, insert it into the CD drive.

If you are using a retail copy of Windows XP then you will find more details
on doing a clean install at the follow link on my website:
http://xphelpandsupport.mvps.org/how_do_i_install_windows_xp.htm

If you are still getting knowhere can you enlighten us as to what is
happening when you insert the Cd and then hit the power? Is the system
simply booting back into XP? Does an error message appear? Have you missed
the screen which says 'press any key to boot from CD?'