You cant cut the music without cutting ALL the sound. Which if you just want to have a preview with music and no dialogue is fine and done all the time.
BUT, all this will be far easier to explain once you actually have an editing program. Get one and start experimenting. It is fun to learn and all makes sense.
Best way to get one? BUY ONE. Circuit City and Best Buy are stuffed with them. You MIGHT be able to download one, but I have never looked, and I can almost guarentee that anything rudimentary enough to be downloadable probably wouldnt be able to do anything worth a damn. But it wont hurt to look.