If you've backed up the complete iTunes folder including the XML files and have not added anything to iTunes yet, close out of iTunes and copy the contents of the CD back into this iTunes folder. When iTunes is launched, it should pick up the restored library.
If you have already added music to iTunes or don't have the XML files backed up (just the music), go into go into your "My Music" folder and create a new folder, e.g. with the name "iTunes restored". Copy your backed up disc into here. Then within iTunes, go into the File menu, select "Add Folder to Library...", select this folder from your My Music folder.