Snowboard jumping technique?

Ok, I just converted from skiing to snowboarding, and on my third time on the board, I decided to hit the terrain park. Now the boxes went well enough but when I hit the big jumps, not so good. Now what I want to know is are you supposed to launch yourself off the end of the jump or just ride it off? I was landing on the flat a few times even though I thought I had some pretty good speed. Needless to say, my *** is killing me today. Any useful techniques?