Put the table tennis balls into the the ball and Fill the koi ball with the required amount of food for your koi. If you feed your fish with grains, sticks or silkworm, then use the closed door but if you give pieces of lettuce or fruit then use the semi-closed door for closing off the ball.
Put the koi ball on the surface, some of the food will come out, the koi will notice the food and swim to the surface. They will eat the released food and then push further against the ball in order to release more food. At the beginning this will require some training, therefore leave the ball long enough in the water the first few days/weeks.
Remove the koi ball out of the water after feeding.