Hi Superlizard!
Congrats on the new board, setting up modern sails is all about downhaul. Here's a good page to get you started:
www.guycribb.com/userfiles/documents/Downhaul%20and%20Outhaul.pdf Basically the order I do things is this:
1. Put the sail on the mast, and pull a bit of downhaul by hand.
2. Set the boom to the correct length, and clamp it to the mast.
3. Tie a bowline loop in the downhaul rope, thread your harness hook through this loop, sit down facing the mast, put your right foot on the end of the extension, and haul like an olympic rower on the harness spreader bar. The top of the sail should be floppy, and the top few battens should be well clear of the mast.
4. Attach outhaul, adjust to the wind speed, and then attach mast to board.
5. Sail away

The base page for Guy Cribb is here:
www.guycribb.com/page0076v01.htm , lots of good info on this page.