I have an Acer computer running windows XP...........?

You need to boot from the cd to restore the computer. Some computer will also use a bootable floppy disc to make this happen so see if you have one. Put the floppy, or cd #1 into the cd drive and reboot the computer. When the first screen comes on you should see a message that says hit the delete key to enter set up. Some mfg may use a different key, but it is the same process. You should be able to find and option (usually under advanced options) to choose your first boot drive. If it is a floppy then choose A: if it is a cd then choose D: or what ever your cd letter is. Exit and save settings to the bios and restart. This should make your computer start from your cd drive to do a system restore.