There's not really much to it. The brushes used are in the picture, but for the bright blue parts of the water, he used a luminosity layer. Airbrush for the bottom light rays, and use the water brush for the lighter parts on top. To blend, use the blur brush. I'm using the tutorial on a drawing I'm working on at this very moment, and this tutorial has proven to be helpful. It'll be harder if you don't have any knowledge about the program and so-forth. I hope I helped you in some way.