There are two different methods I've used. The original pin head Ullman mainsail had a downhaul system you had to thread thru the sail each time you raised it. My newer set of Ullman sails with the square top main has a much better system that hooks up in a few seconds. I'll try to describe it here. If it doesn't make sense I can take a digital photo and email you. Basically there should be a swivelling block with a cam cleat on each side of the mast near the base. On the aft bottom portion of the mast is a cheek block that serves to allow the line to pass thru from the starboard side to the port side to allow the downhaul to be a continuous line. This block attaches into the curf. For purchase you have a set of double blocks and fixed cheek blocks on each side of the mast where the line is threaded. On each double block there is a bail that has a short line with a loop on one side and a short line with a ball(like the one for pulling down your rudders). The purpose of these is to feed the loop thru the large grommet that is about 10" up from the bottom on the luff of your main. This loop then goes around the ball thus connecting the pulley systems thru the sail. If my poor description isn't too confusing I'll describe threading the line. The line passes thru the swivelling cam cleat on the port side-then up thru one of the sheaves on the double block-then thru the cheek block-back up thru the second sheave on the double block-then thru the cheek block on the base of the mast over to the starboard side. From there the line goes thru the first sheave on the double block on that side-then down thru the cheek block on the starboard side-then up thru the second sheave-then down thru the swivelling cam cleat on the starboard side. The ball and loop sections on the bail on the double block simply connect thru thr grommet in the sail. This will give you an 8:1 purchase. I'm getting the feeling it may have been quicker to take a photo then describe it . Good luck! Greg