Facebook connect

Maybe I'm just a dunce, but I just can't find the connect with facebook button on GB.  This makes the quest about linking my profile slightly tricky. 
I know you can create a new account which is facebook linked by using the OpenID login system (or whatever name it has if it isn't an actual OpenID) but can't find the button to add it if you already have created a profile long ago. 
Still getting the hang of these GB quests, but they do seem like a good diversion to stop me going insane while revising and can pop up some interesting pages I otherwise wouldn't have read.  A shame that they weren't stat tracking from the start so the system doesn't know who of us watched the whole first Endurance Run etc. 
Continuing complaining about a free service for my first blog post, why aren't the WM sites linked?  A single login to all the services, a unified user would be ace.  So far I've got 3 different accounts and as WM expands into new areas I might be creating more.  Wouldn't it be ace if they were all kept under a single master account.