To burn an iso to a cd (and I am a Windows and Linux user but the procedure should be roughly the same for Macs) - put in blank cd, open burner program, select the option which says to create the cd from an image.
I would also suggest you go to www.yellowdoglinux.com
and check out the installation howtos. Its a bit different on a Mac than a pc.
Good luck and welcome to the board.