Oops. Big question.
I don't have any specific knowledge about this ship so I'll try to give a generic answer.
Larger ships tended to have two derricks next to each other (port and starboard side of the mast).
This setup allowed one derrick to be in a fixed position above the cargo hatch and the other in a fixed position out over the quay. The tops of the derricks had a line between them so that the distance could not increase. The hatch-derrick was secured with two lines (aft-forward) to eather the sea-side edge of the hatch or some securing points on the railing/bulwark at the sea-side of the ship. The quay derrick was secured in the same way to the quay side railing/bulwark.
The lifting lines for the two derricks were connected to each other, two winches, one for each lifting line. Both winches reels out their lines, the hatch winch slightly slower so that the combined hook hangs down from the hatch derrick. Load is attached, hatch winch reels in until the load is above deck. Quay winch starts reeling in to pull the load over to the ships side, hatch winch reels out to allow the load to move sideways, after a while the hatch line is slack and the load hangs from the quay derrick and line, the quay derrick starts reeling out to lower the load and the hatch winch reels out as well. The load reaches the quay and is disconnected. The process is reversed to bring the hook back in over the hatch and lower it for the next lift.

Try it with two strings tied to a shoe and lift the shoe from outside your left foot to outside your left foot without moving your arms in fron of your body

With only one derrick you had to have three winches, one for the load and one for each swing direction (port - starboard)

One derrick + three winches (maybe three isn't enough either)
or
Two derricks + two winches
A derrick is cheaper than a winch and the two derrick method is faster than swinging the booms.

/ Robin