A file with an .iso extension is probably a disk image file. These files are frequently used to create bootable cd's that you can use to boot your computer from a cd. Certain other cd data might need to be transferred as an .iso file. You can probably use the software from:
http://isorecorder.alexfeinman.com/isorecorder.htm
to burn the image to a cd. You can find other software out there that works too. Do a web search for "iso file" or "iso burner" or "iso recorder" and you should find something useful. Some software will let you view the files contained in the iso image, and you might be able to get what you need without burning a cd.
Merely copying the .iso file to a cd will most likely be useless. You need to use something that will use the underlying disk image in the .iso file.