I am presuming you are talking about an analogue 4 track. You need to record it digitally using the sound card on your computer. Hook the master L&R outs of your 4 track to the line level in on your sound card and record a stereo bounce using whatever software you have at hand. Then burn the file as a .wav file to a CD using Nero or similar.
If it is a digital 4 track (like a PRX4 or similar) then you will want to export a file bounced to two stereo tracks to a computer and them burn it to CD as above.
Good luck !
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