Please Help. I do not understand

A gas station stores its gasoline in a tank under the ground. The tank is a cylinder lying horizontally on its side. [In other words. the tank is not standing vertically on one of its flat ends} If the radius of the cylinder is 1 meterJ its length is 4 meters, and its top is 5 meters under the groundl find the total amount of work needed to pump the gasoline out of the tank. {The density.r of gasoline is 633 kilograms per cubic meter; use 9 = 9.8 mfsa.) Work :[j {include units]