Your title says fireworks but your post says night shows. The approach will vary:
For fireworks:
1) Set to manual
2) Use a tripod
3) Use a remote shutter release
4) Lowest ISO possible (100?)
5) Fairly small aperture (f/16 or f/22)
6) Focus to infinity, then back off a smidge and change to manual focus so it won't attempt to focus with each shot
7) This will likely get you a 5-7 second shutter speed. But it will vary depending on the brightness of the bursts.
For the night shows (maybe MSEP or Fantasmic?):
1) Use highest ISO you are comfortable with
2) Use widest aperture possible
3) Set the highest shutter speed that will give the exposure you want.
The kit lens will be fine for fireworks on a tripod. It probably won't be "fast" enough for the night shows. Most will use a faster lens for these, something with a wider maximum aperture.