Simple instructions for backing a trailer.

Put your hand at the bottom middle of the steering wheel and then if you want the backend of the boat to go left move your hand to the left, if you want it to go right move your hand to the right.
If you get lined up straight and don't take your hand off the wheel you can't make to big a mistake as you can't turn the wheel to much. Keeping your hand on the wheel limits how much you can crank the wheel so you don't get the big swings to the left or right.
Lol, I've taught people how to paralell park too.