To use a catapult, you must first load it with ammunition. Almost everything can be catapulted, but [[rock shards]] and [[stone brick]]s do the most damage. [[Quality]] and [[damage]] of the ammunition will affect the amount of damage done to your target. To load a catapult, double-click an item in your inventory, right-click the catapult, and select Machine -> Load.
After you load the catapult, it must be winched. With every winch the catapult shoots 1 tile further. The minimum distance a catapult can shoot is 10 tiles, the maximum distance is 100 tiles. To winch a catapult, right-click the catapult after it has been loaded, and select winch.
To aim the catapult, simply drag it so that it points to the target.