This is an easy task,
i can tell you how to create a facebook app and integrate it with wordpress ,
either with screenshots or with skype screen share
which ever do you prefer.
Its easy and tricky for the first time.
but i can can you in a simple and clean way.
Simply Put You Will Have To Create A Facebook Application which will hold and Authorise your
users logging [login to view URL] then integrating it with wordpress[ easy part].
No Coding is needed.
all You Need is a facebook and wordpress which you already do.
You Can Tell Me If You Want To Learn More ,