For a first attempt I think you've done very well.
I really like the orangey colour tones and there's some lovely detail in the sky. I love the little seagull at the front too.
Compositionally it doesn't quite work for me though.
I know that this isn't the norm for sunset shots, but I wonder if a portrait style crop would work in this instance?
I don't think that the canoeist and the person in the waves to the right of the surfer are adding to the image and I'm finding them a bit distracting which is why I wonder how it would look with them cropped out.
You have a good, strong vertical line from the sun's reflection, so I think that it could work with a portrait crop. It would also give you some flexibility in terms of getting the main figure on a third.
. . . just a thought, and nothing to lose by trying it :shrug: