That guy is WAY back on the bike, but it may be for a reason you can't see in the picture. He may very well be hauling the front end up because he was nose diving... Either way, a normal jump posture shouldn't look like that. I realize that I'm not a shining example of posture, (This is only this bike's 2nd time out after a 3 year break) but I do meet all the wickets for what's normally considered "correct" air posture, a lot like what Ken described above. Anyway, take a look at this...
You can see that if I was to look down, I could pretty much read my front # plate. (If there was a # on there, it's only 3 weeks old) That's about where you want to be. The other info posted here is good, start small, really small. If it wasn't so embarrassing, I'd post a picture of the jump I learned to jump on, but I will say it was made in about 5 minutes with a shovel. Now, however, I'm comfortable with doing 100' tables (the picture is about 65') And when you crash, and you WILL eventually crash, get up and try it again. Best of luck to you...
The stupid shall be punished, usually in a very grand way that will show up on the evening news...