Place a carpenter's level on top of the freezer. Note the location of the bubble. You want the bubble to be centered between the two center lines.
Tilt the whole refrigerator back so that the bottom front is off the floor. You may want to have another person assist in this step.
Locate the leveling legs underneath the front of the freezer. Turn the legs clockwise to lower the legs and counterclockwise to raise them.
Lower the refrigerator back down onto the legs and check the level. Keep making small adjustments to each leg until the carpenter's level bubble is centered.
Open and close the freezer door multiple times to ensure a proper seal.