Headmaster: "Your next lesson is to figure out how to take control of your dragon in the air. Talk to Hiccup and he'll help you figure it out."
1- Go to the Flight Club tower at the Training Grounds
Hiccup: "Welcome to Flight Club!
2- Practice gliding in Flight Club
Hiccup: "Good job!
3- Return to the Headmaster
Headmaster: "Hiccup told me about amazing progress in Flight Club. Good job!"