play the mp3 on its own, does it sound like music?
if no -> well thats the end of that
if yes -> your ment to use that tool to crate bin files (from memory) that you then write to CDR (in the correct mode dont ask me what it is right now), and the CDR well appear to be a music CD, but has the CDG data written onto it in the error correction data, and if placed in a cdg player well play as an original. If its not your likely writing it in the wrong mode, seek the toolz help files.
PS: Mirc isnt responsible for downloaded CDG files that dont work, and also alot of them CDG files are copyright (although i feel thats a bit dodgy sometimes since i have seen the mp3 being the original score, with out rights to use it being seeked)