What happens next?

How to execute flying kicks (twimyo chagi) in taekwondo
Make a running start towards the target and jump off the leg you are not going to kick with.
Fly through the air (several feet to several meters depending on your ability) and make contact with your target. The leg you jumped off from should be pulled up close to your body (including your hands) after you are in the air while flying.
It is vitally important to keep your body protected from falling while landing. When the kick is completed, return to a good fighting stance.