What command can I use to backup certain files and burn them onto a blank CD? I tried "copy c:\myfiles d: ", but it says "access denied" to the files. It's a writeable CD. Is there something I have to do before I can burn files onto it?

You need a special program such as DirectCD in order to write files to a blank CD as if it were a floppy disc, just as you need a program write an entire CD at once. Just using the copy command will not work. Also I do not know of any CD-Writing programs for DOS. You'll need Windows and a program like Easy CD Creator or Nero Burning ROM. You might want to consider getting something like a Zip drive or MO drive in order to just quickly copy files from DOS.

You leave a lot of puzzles with your question such as what CD recording software
do you have. Now days you usually drag and drop what you want to include on the CD-R. With direct cd for (CD-RW) you have to format the CD-RW first.
I have found it easiest to make a
whole cd at a time. I make an extra logical drive for this of 730 Megabytes (for fat16 and 680 megabyte disks) I put everything I want to save on this drive and make the CD from this drive when I am ready to record.
The software I use (Nero or Easy Cd Creator usually) does not use copy commands. You drag and drop or you use the same interface as Windows Explorer to select items with.
I do not know how to make a CD-R with a batch file, but if you had a logical drive set aside for CDs, you could use XCOPY in the batch file to copy data to it for recording later.

Thanks a lot, guys. You were very helpful. I think using a zip drive would be the best bet. Should I just be able to use the copy command for that?