I snowboarded for two years, when I worked at the ski resort. Good times.
First time I went I ate shit so hard bashing my knee open. Moral of the story, have someone show you how to stop before standing up at the top of the mountain.
Simple as this, keep your knees bent and lift your heels, then put them down and lift your toes distributing your weight in accordance. Have fun, don't eat shit, and watch out for beginner skiers. Their little s thing they do sucks ass. Its always the S'.