a usb flash drive would be better than a cd/disk unless you have a bunch of disks around already.
disks get scratched easily and may not last as long as you want them to

flash drives are enclosed with a memory chip
and you don't have to burn ( copy/write to a cd) anything to use a flash drive.

basically just click the file or files you want to backup and send it to the flash drive easy


http://www.udel.edu/topics/backups/flashdrive.html
http://www.backupforall.com/usb-flash-backup.php

there are probably many videos on youtube and websites that detail step by step how to back up your computer..
much easier than me trying to type everything out..

http://www.google.com/#hl=en&cp=13&g...w=1360&bih=636