Assuming you have downloaded and installed Boinc, you'll need your WCG Boinc ID info to "attach to the project". Go to your "My Grid" page at WCG, sign in and click on "my profile" (2nd tab on left hand side of screen), and scroll down to the bottom. There you'll see your Boinc Account Key and Project URL. Copy those to notepad and save them.

When you install Boinc, it pops up a window that says "attach to project". Alternatively in BOINC Manager click on Projects then Attach to project.
You''ll need to paste the URL in, then your account key.
It should connect to WCG and start downloading work units. You can set your preferences in the tabs at the top of the Boinc manager window.

Then you need to go to your "My Grid" page and Device Manager, and you should see a "Boinc" machine listed. Once again, click on "default" and it will open a page where you need to select your preferences on how the program runs.

(Adapted from our team member LP's instructions at AOA Forums)
http://www.aoaforums.com/forum/lps-a...ugh-boinc.html