Hello,

I am running Ubuntu, and I was going to try and install windows xp again because I was to new at linux but I don't know how to boot from cd with linux. So please if anyone knows how to teach a newb about booting from a cd on Ubuntu please reply.

I am not sure what you are asking but here goes anyway.
Booting is the process that occurs after the POST process and the system launches a basic or full operating system that allows interactive control by the user. This is controlled in most modern computers by telling the bios to look in a specified device for the operating system. If you want to boot using a cd then get into the bios (normally done by pressing the Del key after the POST process) and tell the computer to boot from the cdrom.
If this is not the info you are looking for please could explain more fully what you are trying to achieve.

Well, if I understand you right, that's nothing special about Linux. If you can boot from CD is managed by your BIOS. Since you managed to install Linux this seems to be the default with your computer. Put in the CD, do a soft or hard reboot -- et voilà!