I've been reading that Starcraft 2 has facebook integration. But how do I actually connect my accounts?
If you log onto battle.net, go to your "Home" page by clicking the little house button.
As you can see there, is a button which says "Import Friends" next to the Facebook icon. Select this, and enter in your Facebook credentials.
If the broadcast has expired, select your friends:
Click "add friends":
Select "add Facebook Friends."
As of January 2013, Facebook integration has been removed by Blizzard because Facebook
[...] changed their API usage policy and decided to prevent third-party games like StarCraft II from utilizing their network to make social connections.
Click the friends list button at the lower right hand of the task bar (left of the clock/mic)
there will be a button for 'add friend'
Click that and you will see a button for facebook.