Fireworks displays are generally very stunning and colorful. To capture those moments with a camera can be quite is a challenge. It is essential to use a tripod to hold the camera steady. Tripods can be inconvenient to use however they are almost essential to get stunning images. A cable release can also be very usefull to eliminate camera movement.
Find a suitable spot where you will have a clear view of the fireworks display. Also try to stay away from any street lights which may introduce flare into your lens.
An exposure time of around 1 to 4 seconds is generally good, you may even like to use shutter speeds longer than that. Use an ISO speed of 100 to 200, that should keep the camera sensor noise to an acceptable level. An aperture of f/5.6 to f22 would be a good range to try as the value will depened on the brightness of the fireworks.
Set your focus to infinity and set the camera to manual focus. Bring a small flashlight so that you can see the camera controls. Turn the camera flash off.
A multiple exposure to capture many bursts of fireworks on the one frame can add greatly to the visual impact of your fireworks images. An example of a multiple exposure is shown below.