This is the second squaresail from the top on the foremast. You start by squaring the yard, pivoting it so it is athwartships; this is optional, but it makes for a fairer lead for the halyard. Then you slack off the sheets of the royal, which is above the topgallant, and which otherwise helps support the topgallant. Then you ease the topgallant halyard while simultaneously hauling on its clewlines, making the yard slide down 14 feet or so until it comes to rest in its lifts, just above the top of the topmast. Then you ease the topgallant sheets and continue to take up on the clewlines, pulling the bottom corners of the sail up to the yard ends. Then you take up on the buntlines to cinch up the belly of the sail, and make sure all lines are properly snugged and belayed before ascending the ratlines (I won’t even go into the challenge of traversing futtock shrouds), laying out on the yard (basically walking a tightrope sideways) and leaning way over the yard, belly down, to pull the sail up, bit by bit, to furl it. Then you lash it to the yard, still balancing on the footropes, and all the while the ship’s roll is slinging you back and forth on maybe a 30-foot arc. When you are done aloft, you get to climb all the way back down to coil the several hundred feet of rope you have left strewn about the deck. And that is just for one sail.