Quick and dirty: Play the midi on your computer and record it with your tape machine. This converts the noise the midi plays to an audio (analog) signal on the tape. Play the tape into your soundcard and "record" to the hard drive. The computer should record it as a .wav, which you can burn onto a CD that your CD player probably can handle. (Test it, on the player you plan to use, to make sure it works.)

There are "better" ways of doing it, but most of them require software, and instructions somewhat specific to the particular program(s) you have available.

Alternative: If you've got one of those newfangled portable keyboards, or another midi "instrument," some of them can play the midi directly from a floppy disk.

Quite a few church organs can take a midi on a floppy disk and play it back for you, but you'd need to check it out with the organist (some of them are a little "possesive" about "their" isntrument, among other reasons) - and test first. (And you didn't say its a "church wedding, of course.)

John