I used to think that capturing fireworks on film was laden with technical wizardry and talent, but after giving it a whirl with no advice or instruction, I discovered it's quite easy. Here's how...
As you can imagine, a tripod is at the top of the list for equipment! A remote cable release is up there as well, but that's about it. Assuming you have a digital or film SLR (single lens reflex) camera that you can set to bulb mode, you're off to the races. Film choice is arbitrary, but I highly recommend transparency film at 50 or 100 ISO. That's right - I said 50 or 100 ISO. But you may be thinking "...it's dark out!". True, but the light trails left gehind on film or CCD from fireworks is quite bright, plus we're not trying to expose for everything else surrounding the area. Print film will work as well, but the colors won't be as vibrant as slide film.
So - your camera is on a tripod, it's in bulb mode, and a remote cable release is attached. You need to compose the shot, so let a few fireworks go off to get an idea of their expanse in the sky. A zoom lens is great to have in this case, as you may not be able to locate yourself ideally. Also, I find tilting the camera into portait mode works for most fireworks displays. The tighter you can compose, the more detail you'll get in the final product.
Exposure length is up to you. After you see (and hear) a charge go off, depress the shutter via the remote, and let some drama happen. Perhaps 3 or 4 separate explosions have happened, and the've died off... close the shutter. I've done anything between a few seconds, and 30 seconds. It all depends on the fireworks themselves. Settings for 50 and 100 ISO film can be anything between f-5.6 and 11, with focus at infinity. I usually stick around f-11 - that way good focus is guaranteed and you won't over-expose if there's alot of white in the fireworks display.
A fun trick is to keep the shutter open in bulb mode - and use a piece of dark or flat-black cardboard as your shutter. There can't be any extreneous light around the camera to cause light flares. Just use the cardboard to block light reaching the lens, removing it to expose the fireworks at your will. I've used my 18% grey card for this quite successfully.
Good luck, and let me know if this has been helpful!