Don't worry about the perspective of cylinders yet, its an amazingly complicated thing to deal with. A quick and dirty way to do it with photoshop is to draw a box in perspective and then use transform to place a circle on each end. Of course that means you have to put the box in proper perspective. If that is too much right now, just keep on working at the classes, there is more about that later on.
But the exercise that you were doing is about capturing the feel of the model and I feel like you are on track. Pay close attention to the tilt of the hips and shoulders while you are working on this.
I look forward to seeing more!