Yep, all NoStopping said is correct.
If you're new at jelqing, you should start with an erectio between 60%-80%. Do do it fully erect, as it can be dangerous because your penis is not used to that kind of internal pressure. Get a good semi-erection and start from there.
And do as he says regarding expansion. It's not easy to actually see it happening, because your penis moves slightly when you jelq. So the best way is to feel it with your hands.