Before you burn an audio CD, it helps to check out whether you have mastered your CD first...

Play a commercial CD, then play the audio files. Rip a track or two (or three!) from the CD as .wav's (many MP3 players adjust the volume of tracks, you don't want that this time) and play it in the same software you are listening to your tracks on. Try to pick something similar in vein to what you have done (oldies for oldies, jazz for jazz, etc.), and try to not play something mastered recently (no 'remastered' original recordings, as modern mastering levels are too high IMO and tough to match as an amateur).

Now, does your music sound MUCH quieter than the CD? If so, try getting hold of a limiter and compressor software (I'm not PC so probably can't advise, but just google it). There is supposed to be some decent stuff available as freeware or cheap software.

Try some of the 'gentle master' presets to start off, and see if you can bump up the volume without affecting the track much. Don't go overboard, close enough is close enough, but if you do this stage first, your CD will end up as a more polished package.

While you are listening and comparing tracks, that's also a good time to check for whether yours sounds overly bright or bassy compared to the commercial CD, and a hair of EQ can help out.

Don't skimp on the mastering, it's the icing on the cake!

(apologies if you have already done this stage, I just know so many people that skip it then wonder why their CD sounds so QUIET!)