Don't know why only one person mentioned this but you gotta loosen your arms up, relax a little and everything should take care of itself.
these are from bike radar. didnt post a link coz I dont know what mtbr policy is.
Approach the jump standing up out of the saddle with your arms and legs relaxed, your cranks horizontal and your natural foot forward. This is the 'attack' stance and it allows your body to move as it needs to. Keep your eyes focused on the take-off, but also make sure you're scoping the landing. As for speed, building up from just being able to roll over the jump will tell you how fast you need to go to clear it.
Push your legs into the take-off and follow this motion with your wrists to keep the bike following the trajectory of the transition. Stay relaxed here; tensing can make the bike 'buck' off the lip awkwardly, which will throw you off line and possibly to the floor. Keep your weight as central on the bike as possible: leaning forward will lighten the rear end, causing scary nosedives, and leaning back could have you off the rear of the bike.
 Levelling out
As the rear wheel comes up, the bike will start to level out. At this point, keep your weight balanced to prevent the rear wheel rising too high. Make sure your arms and legs are relaxed because this is your 'air time'. If you're tense, you'll be on the edge of control and you risk pummelling into the ground. Allow the bike to naturally follow the curve of the jump - think of a dolphin leaping.
 Spot the landing
When cruising through the air, you have to make sure you spot your landing and also the run-out area. You only need to glance at the landing ramp for a split second because your first instinct will be the right one. Look at its shape and ignore any bumps and lumps that may be bothering you - you'll be going pretty quick and so you'll roll over these. Don't stare at the landing too long or you risk messing it up - you need to look ahead as well!
If your bike is still level, extend your arms slightly and tuck your legs up a bit to allow the bike to follow the transition of the landing. Ideally, you'll be nose-diving slightly, ready to 'scoop' into the transition for a smooth landing. Avoid touching down rear wheel first because the front wheel can wash out if you're skewwhiff. Likewise, avoid steep front wheel landings so you don't go over the bar. Also look ahead for obstacles as you absorb the landing.