Although fairly straight forward, fitting and setting up an Ahead set is not something you should do if you are unsure of the proceedure, it can result in broken frames, broken forks and broken faces, not to mention egos.
Take it to a friendly shop and ask to watch it being done so you can learn, they'll usually charge a tenner to fit a headset, tip them a little more if they let you watch - biscuits/cakes or beer usually suffice.
And make sure you have that Pace shim you need.