OK wait...now I'm confused. The halyard should be a cable halyard that has a small "BB" (who said that? - good description) pressed on it about 12 to 18" from the shackle that connects to the head of the main sail. As you hoist the sail, this BB goes through the two sheaves at the top of the mast until it (and the rest of the halyard) is on the front of the mast and the sail fully hoisted. There is a fork at the top of the mast that you manuever the halyard into, and the BB under. Then you ease off the halyard and/or pull down slightly on the mainsail and the BB engages the fork way up the mast. It can be a little difficult to see. After that, you just tidy up your halyard and pack it away - no adjusting from there. You should have some sort of downhaul that attaches to the clew (bottom leading edge) of the mainsail that will involve pulleys and a bit of purchase.

Note: The BB exerts a pretty tight bend in the cable everytime it goes over the sheaves. The cable halyard will eventually break right at the BB...it would be worthwhile to have a spare halyard or some sort of backup plan.