Here is a tutorial of how to do it. Just to let you know I didn't do any editing to these. I actually thought, hmmm how can I edit these in a way that they can look cooler. You guessed it, I couldn't think of any way to edit. These fireworks are just amazing with out it.
1. Make sure that it is completely dark outside.
2. Keeping the image in focus is also kind of important. What I did for this, is I put my camera on the highest aperture. I put mine at 20, which I think might have been a little excessive! You would be fine with an aperture of 12 plus. I focused on an the trees that were right above the fireworks. That worked well for me.
3. Make sure that you aren't close to a light post. Even if you feel like it wont be in the way, most likely it will be. We were kind of near a light post, so I thought it was going to be okay, but it ruined a few of my pictures. Sigh haha :D
4. Always bring a tripod (you will see why in the next number).
5. Have a long exposure (shutter speed) so that you can get the trail of the lights. Because of the long exposure you need to make sure that you aren't moving your camera at all. I also click the shutter when I hear the firework go off, which can at times be easy or hard to hear.
All these image were shot with my Canon 6D with my EF 24-70 F2.8. I kept the aperture at 20 and the shutter speed around 3-5 seconds.