First jump, then, while in the air press and HOLD the jump button a second time to activate the jump boost. Once your jump boost wears off, let go of the jump button right away. Press the left thumbstick, then, while holding it down point it in the direction that you are jumping. You should fly quickly forward in the designated direction. Once that wears off, you can repeat it several more times in rapid bursts to lenghten your jump even more.