Snowboarding
I love snowboarding!! I try to make it up to Denver every year.
Anyway, for the op: Make sure you clinch your fists when you think you are going to fall. You want to watch out for your wrists. I have a cousin who broke her wrists when she first started out. Other than that just enjoy it. You will probably walk away a bit stiff with a couple of bruises but it's all worth it. :)
On a side note: Skiing is gay. :P
I know this isn't snowboarding, but when I went skiing, I accidentally went down a black diamond as my first hill. It was crazy. Since then, falling down never really bothered me. It has actually become rather fun. Like, I won't go trying to fall, but I'm not afraid of it either. A few bumps here and a few bruises there never hurt anyone.