Barkingdog,

The general rule of thumb is a 45 degree angle down measured as if a plane(not in the sky) was leveled across the top of the bar horizontally.

Here is a link to a something that will walk you through it. There is no need to go back to the LBS unless you have other questions as well or just want them to explain it better to you. Scroll down to page 5 of the link I wrote in above. It should help you out. If you are planning on getting into some of you own bike maintenance (you said the LBS was a drive), picking up a set of Barnett's manuals is the best thing you can do. I find trying to download/use/print them offline to be more trouble than its worth. I picked up a set a while ago after I had gotten pretty proficient at doing my own maintenence. It has been one of the best bike-related purchases I have made. I think that you can find the whole set for something like $100 at a big bookstore like Barnes and Noble or Amazon, and youn can get the individual books for something like $30 a piece at the same places. The set contains all four books, each dealing with a seperate area of the bike. The last book in the set conatins worksheets that are made up of shortened versions of the steps in the original chapters, as well as check-offs to keep track of how far you have gone. The worksheets do not contain all of the paragraph-text of explanations as in the full chapters, and are meant to speed up the process once you have done the repair a few times by eliminating any information that it is assumed the mech knows. Good luck!
-Moab

EDIT: My link won't work. Go the mechanics section of the forums, click on the Barnett's manual post at the top of the page, and look for the index. Click on brake levers and scroll to page 5. Everyting you need to know is right there.