Very nice shots for your first attempt!
I love shooting fireworks, but I am by no means an expert.
From my experience, I can say that there are several factors to consider when photographing fireworks. First, I consider lens selection and distance from the fireworks display as the biggest factors affecting camera settings. If I'm shooting from an (ideal) distance of 400-600m away from the launching spot, I'll choose a lens in the 35 to 70mm focal length range. If shooting from a distance of 400m or less, I'll use a wider-angle lens (approx 28mm), and for distances of 1000m or more, a 70 to 100mm lens is good.
Clearly, every fireworks burst is different, so there is often a bit of luck involved as well. Sometimes, if you're really motivated, you can contact the event organizers and obtain a "schedule" of the planned display bursts. But such detailed information isn't always available.
As for specific camera setup and exposures, I generally "start out" with something like these (below), but you need to be flexible, and be prepared to adjust on the fly.
Aperture setting around F8 – 16 (F11 for starters)
Focus at infinity
Shutter speed on “Bulb” - Exposure time is 1-10 seconds depending on intensity of the burst. For a typical "Chrysanthemum" burst, I'll expose for 2-3 seconds (just by counting silently in my head). For the really bright "starmines," I'll press the cable release button and then release it very quickly -- maybe 0.25 to 0.5 sec -- otherwise you risk overexposure.
In summary, there are no "absolutes" when it comes to fireworks photography, and I'm sure there are many other opinions out there. But this is my general approach. Best of luck!