[edit] Steps

Set yourself up going straight on with the jump with a decent amount of speed.
Lean toward the front of the board.
When you get to the lip of the jump, spring off the nose of the board and send your weight forward.
When you are in the air it is hard to spot your landing because you are inverted, but don't worry because when you flip you will either land on your board or under rotate the first time so you land on your butt. It doesn't hurt that much if you practice on a smaller jump.
Just keep practicing and you will master it after a while.you will get the hang of it!

[edit] Tips

Don't be afraid to fall, because you will fall. Always wear a helmet for safety.
Always ride with a friend so if one of you gets hurt the other can call for help.