You first need to make sure that your PC is set to boot from the CD before the hard drive. When you first turn on your pc you should see at the bottom of the screen a command to press (usually Del) to enter set up. Press and hold the key mentioned and the bios will appear. You will have to find the boot options, which differ according to the bios. On mine they are under advanced cmos funtions. You will see the drives listed as Floppy; CD-Rom and HDD0 (your hard drive). Make sure that the first boot drive is the CD-Rom. You will then have to find the option to save and exit (usually an F key) and then possible say a further yes by pressing Y. Insert your XP CD and restart. You should see briefly at the bottom of the screen the command Press any key to boot from CD. Hit the spacebar. The Windows setup screen will appear on a blue background and you will see files loading at the bottom of the screen. Allow this to run until complete. When prompted press enter to Set up XP. Press F8 to accept agreement. Press Esc to install a fresh copy of Windows as per the prompt. From the options at the bottom of screen press D to delete the partition and return to confirm, then press L to complete the deletion. At the next screen press C to create a new partition. Accept the default size. Press enter to continue setup. If asked choose a file system, Fat32 or NTFS. You drive will be reformatted and some files will be copied. Set up will initialize and the computer will restart. Ignore any further prompts to boot from CD. XP will install. During installation you will be asked for regional and keyboard settings etc., and also network setings (typical should be ok) Make sure you answer correctly. When complete PC will restart. Again ignore prompt to boot from CD. When running remove CD. All done. Activate It. Good luck.
You do not need a floppy. The location of boot options will depend on your bios. Did you get a manual? Also your bios name should be the first thing that appears on the black & white screen when you switch your PC on. Make a note of this if you cannot find them and post back.
If you look about five lines up I did say that your drive will be formatted.