If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
Real skill is not about scoring goals; its all about how you handle the ball.
Left / Right Arrow Keys - Walk.
Left / Right Arrow Keys + X - Cartwheel.
C = Handstand
Left / Right Arrow Keys + C = One-Handed Handstand.
Spacebar - Hit the Ball into the Air.