The mountain board works much like a snowboard. Unlike a snowboard, it has wheels and hurts alot more when you fall. You turn by shifting your weight to either side of the board. Always remember to keep your balance and not to turn to far.
Jumping is a little more difficult than turning. If you have a leash pull up on it and do small wheelies. This will also help on bumpy courses. Once you get this down you can try to jump. When you pull up on the leash also pull up your leg to lift the back. While in the air straighten yourself out so your level with the ground. When you land keep your knees bent so you won't break your leg.