Bonnie

It is easy to do. Separate into two sections behind the head. Take one and start to twist it one direction near the nape. Do a few twists, then hold it if you can with your ring and little finger so you can use the thumb and index to help twist the other side (go the same direction IE: counter clockwise). once you get a few inches of each strand twisted you are then going to take the and twist around each other in the opposite direction.
I can usually do this for about 3-4 turns, then have to bring it around my shoulder to finish. This part is tricky, I find if I close my eyes I can do it without thinking (because you need to do everything in reverse). Finish to near the end and tie off.
The braid will loosen somewhat - so try and get as tight a twist at the start. It does help to do it on damp or oiled hair if you want a really compact look.
I use it as a "sleep braid" because it doesn't give me braid waves the next day - I am plenty wavy already and prefer a smoother look.
PS - I am 60 and have fingertip length hair (upper thigh) and going for knee length, just to see if I can do it. My hair is still pretty darned thick so I figure why not. I think I will post a hair pic as my "before" photo ... lol.