One way to get the desired affect, in future, is to take two shots in quick succession. Expose one shot for the beach and the boat, and then without moving the camera, expose for the sky. Once back home, combine the two images and then you will have the right exposure for the whole shot.
As for editing that image, im not really very good at that yet as im fairly new to image editing as well. But in general, the whole shot looks slightly over exposed?
I think the first thing i would do is reduce the purple tint to the stones on the beach, up the contrast a tad and fiddle around with brightness. As for anything else, a more experianced member of the forums might be able to help you out.
Woodsy