More information is needed. What hardware and software are you using and how are you attempting to use them?
If you are using a DVD burner with appropriate software you can backup to a DVD rewrittable disk. To do this format the disk for drop-n-drag. Then that drive will operate just like a floppy disk. Can save there as you want using usual methods.
With additional information maybe others can offer more assistance.
I have forgotten how to backup files to DVD. Need help ----------have Windows XP home edition Please help.