You can shoot your cannon every five seconds. You must adjust for the wind, then set the proper angle and shoot. Try to hit the opposing hero to get more coins. Shoot down the enemy dragon, soldiers, orcs, etc. with your cannon or other defensive units. Send some cannons out as your enemy will try to destroy them first and thus will save you a few cannonballs. If you have an Orc at your castle's door, send a Soldier to kill it. Orcs, Cannoneers, and Bombers are used against castles themselves. The wind changes at random times. Watch the flag to judge the power of the wind. The best way to shoot is to keep the aim bar at about three quarters. If you can hit a specific enemy room enough times, you will completely destroy it. If one of your own rooms is in danger of destruction, quickly repair it.