Choose your player and start the round by performing boxing moves just like the real one. Be faster than your opponent to knock him out.
Enter the fight like a real boxer and face your opponent with different fists to knock him out. It is quite difficult to execute the perfect shot but with each lost round you will learn more about this sport. Defense is the most important thing, wait for the right moment to hit when it is optimal. You can always change the fighter with the desired one so that the game experience is as pleasant as possible.