If you need the front wheel to come up, you can increase the throttle, and engine revs. This will raise the front.
If you need to drop the front, use the back brake to slow the rear wheel down, this will drop the front. Make sure you have the clutch in if you do this one.
Both methods are quite advanced, and need fairly large airtime to notice the effects.
Its probably easier to adjust your approach the jump to ensure that your throttle position is correct when you launch while you are learning.
Engine control
If you need the front wheel to come up, you can increase the throttle, and engine revs. This will raise the front.
If you need to drop the front, use the back brake to slow the rear wheel down, this will drop the front. Make sure you have the clutch in if you do this one.
Both methods are quite advanced, and need fairly large airtime to notice the effects.
Its probably easier to adjust your approach the jump to ensure that your throttle position is correct when you launch while you are learning.