Whoo!!! Not too bad for an hour! I like the contrasting colors between the body and background.
So the first thing I noticed that could use improving is the background color. I know, i know, I just complimented it XD I like that it's blue, but it's too saturated. It's so blue to the point that it starts distracting from the focus of the picture, which is the male figure. Picking a more grayed blue would work a lot better. You could also bring some of that blue into the skin of your figure to unify the picture better. Digital painting can be super hard. I'm still trying to master it too XD I go to Ctrl+paint.com for digital drawing, painting, and even some basics that are very useful. Investing in the more premium tutorials are worth it too.
The anatomy could use improving too. The chest looks pretty good, but the arms look thin in comparison to the rest of his body. If you come back to this one and decide to add to it, it should be fairly easy to add more mass to the arms.
Otherwise, keep at it! Practice makes perfect and I think you're going to just keep getting better and better!