gistfile1.js

...
}, function(){
    // run code when connection is ready
    $('body button.login').click(function(){
        flex.social.facebook.login(function(res){
            flex.social.facebook.getUser(function(userData){            
                console.log(userData);
            });
        });
    })
...  

// in body section create login button 
<button class="login">Login with Facebook</button>