1) As mentioned, you need it on a tripod.
2) ISO 100 or 200
3) As mentioned, use a remote shutter release
4) Set the shutter speed long or use "Bulb" so you can decide with each shot. I think most of my shots are 4-7 seconds
5) Aperture f/11 (give or take)
6) focus set to infinity
Have fun! "Shooting" fireworks is a lot of fun!