"System Restore" and restoring from a backup are two different things. I know...it doesn't help that Microsoft called them by similar names.
System Restore takes a snapshot of registry changes, driver changes, and things like that and saves them on (usually) the same drive that the operating system is installed on. This is done through Start -> Control Panel -> System -> System Protection.
Restoring from a backup is an entirely different process. Files, folders, and whatnot that are on the backup media (in this case, your DVD), are copied from that medium back to your computer, (usually) overwriting what's currently there. This is done through Start -> Control Panel -> Backup and Restore, as the tutorial states.