In order to write any file to a CD you must first create an iso99660 file system on your hard drive using the mkisofs command. Then you use the cdrecord command to write the iso9660 file system to your CD-RW. See:
There are GUI front ends for burning CDs. If you want to use a GUI then try GnomeBaker:
Once you have created a backup CD you can retrieve the files by mounting the CD and copying the files from CD to hard drive using the cp command or a file manager GUI. If the files on CD are tar files then you can also retrieve them with tar.
If you have enough space on the CD for the files without having to compress them then I recommend that you not use tar. Use mkisofs and cdrecord (or a GUI) to create a copy of the directory tree you are backing up. That way you can browse the directory tree on the CD and do partial restores.