Blogs Mu - Join our community now button

I may have not installed this correctly to work the way it is supposed to. I have multisite and my primary domain is not the area where I installed this theme. So as an example lets say my primary domains is and I installed this on When I hit the "join our community now" button it goes to even though it was installed on So I need to know where can I change the link so it goes to some other location. I am very new to this but I learn quick. It appears that this button should go to a sign in screen or something. All help appreciated.