Generally you can stick in a blank CD-R or DVD-R into a CD-R or DVD-R drive.
After that process is completed, and if the drive recognizes the disc, you should see a window that comes up asking what you want to do next.
Choose to OPEN A FOLDER.
In that folder you can then drag in any files you want to back up.
On the upper left hand side, you can then choose to BURN.
Wait a few, and your data is backed up.