All of the programs they suggested for digital art are great, but to get an idea how to have your character's body positioned, you're going to want to find some reference for your drawings. An excellent source of photo reference is the Muybridge books. Just look up his name on google and you'll see plenty of photo's from his books.
If you are just looking for a simple breakdown of how to draw it, check into the Preston Blair animation books. The image below is from that book and may be all you need:
Also, you might want to try just doing it on paper and then scanning it into the computer. That way you can see through your pages while you draw and keep the proportions right. You can then use the other mentioned programs to either trace your rough sketches or clean them up. Hope that helps.