Nero doesn't open the ISO image... off-hand I don't remember the exact steps to use Nero to burn an ISO image. Just to be clear, you don't add the .ISO file to a new "compilation".
If the CDR can't even be read after burning, then it's almost certainly a coaster. You can try again, and report what you find. In the future, I'd suggest against buying no-name Fry's media.
You should consult some documentation to get you started on the install procedure if you're a newbie. Search/browse through the Operating Systems forum to see some suggestions. I can't think of any off-hand, but I assume Mandrake's web site has user manuals.