A legal jump shot is played by striking down on the cueball jacked up, and bouncing it off the slate, over an offending ball(s), onto the object ball. Scooping the cueball from underneath is a foul, and may seriously damage the cloth.
A legal shot, when properly executed, with the intention of jumping the cue ball over a ball that is in the way in order to hit or pocket an object ball. It is a foul to jump the cue ball by miscuing (scooping) it over the problem ball. See a local professional for more information concerning how to jump a ball legally.