Hey Rollerkingdom,
Not bad. I think there are some things you've done well, but I'll just talk about what could be better.
First off, the anatomy. It is not terrible, but there are certain things that make it look very off. First, his right arm is much too long. You should be measuring each segment of each arm and leg as you make them to ensure they are the same size. Next, his left leg appears to be broken at a weird angle. His legs are too short. Remember that from the bottom of his buttocks down, should be half his height. I drew a skeleton over top of your guy so you can see the errors, then drew my own to attempt to show you how you can fix them:
First I outlined your skeleton, then drew a new one:
Then, I twisted your guy to fit onto my new skeleton:
Here is yours vs. mine:
Always keep in mind how many, "heads" tall you want your guy to be. In this one, he is right between 5 and 6 heads. I went ahead and made my guy 6 heads tall. There is still stuff wrong with mine, notably his right arm is still deformed. The upper arm should be shorter, and the lower arm longer. The face doesn't quite work either, it feels too crowded onto the small space you have to work with.
As for non anatomy things, you are using a heck of a lot of colors. This is something that I am still learning a lot about, but you need to learn to eliminate similar colors. On the guy alone no background, I counted 54 colors. There should probably be less then 20, maybe closer to 10.
The background is alright, but kind of boring and also color intensive. Having a perfectly flat horizon like that isn't very realistic, and since there is a mountain back there, why not make the horizon shape into the mountain? Also, the ground pattern looks a little too repetitive.
Hope some of this helps, good luck.