The development team come for this online 3D tool with this intro:
Monster Mash is a new sketch-based modeling and animation tool that allows you to quickly sketch a character, inflate it into 3D, and promptly animate it. You can perform all interactions in the sketching plane. No 3D manipulation is required.
This tool come with three basic steps and modes of creation: Draw, Inflate, and Animate.
Just draw and use these steps.
You can find many tutorials on youtube, let's see one example: