To start off, set up a scene with a groundline, as we don't want our stick-man walking in empty space. Then build your stick figure (you can draw it freehand or use the Line and Oval tools; I did a combination of both), referencing the first pose in the Preston Blair cycle to position his limbs.
To save some trouble redrawing things, we're going to cut a corner that we couldn't do if we were doing this by hand using paper, pencils, paint, and cels: we're going to duplicate the body and head across different frames, so build your stick-man on different layers. I put my head and body on one layer, my arms on another layer, and my legs on a third layer.
A common trick in animation is to make the limbs on the "far" side of the body a slightly darker color so that 1.you can distinguish between them, especially in cases such as this with a simple shape, and 2.so that the shadow makes them seem to recede into the distance.