You add hydraulic fluid to the pump/reservoir in the boat. There is a round head stainless slotted screw near the top of the pump/reservoir, facing up.
Check out the color of the fluid in it, as it could be 5W-30 motor oil (brown) or ATF (red). The pump/reservoir is self bleeding. The cylinders need to be bled manually. One of the other members has the procedure for this. Maybe he will post it.