I just set up a blog and now I want to register users. Do they need to be registered with 3 fat chicks before I can add them as users on my blog?

I went to users on my dashboard and it says to "Add user from community" Then you add the email address and click on the "role". I placed in email address of a friend and it says "User not found. Please ask them to signup here first."

Thank you for any help.