How to use facebook api for login Or register on our website?

<!--facebook login-->
add latest jquery file on the top of the file
<div id="fb-root"></div>
<script type="text/javascript">
            window.fbAsyncInit = function() {

                FB.init({appId: 'your api id', status: true, cookie: true, xfbml: true});

                /* All the events registered */

                FB.Event.subscribe('auth.login');

                FB.Event.subscribe('auth.logout');      

           

            };

                

            (function() {

                var e = document.createElement('script');

                e.type = 'text/javascript';

                e.src = document.location.protocol +

                    '//connect.facebook.net/en_US/all.js';

                e.async = true;

                document.getElementById('fb-root').appendChild(e);

            }());
           
       
    function customFbLogin(){
            $(document).ready(function(){           
                FB.login(function(response) {
                    FB.api('/me', function(response) {
                  var query = FB.Data.query('select src_big from photo where pid in (select cover_pid from album where owner={0} and name="Profile Pictures")', response.id);
                 query.wait(function(rows) {
                                alert(response.link);
                               alert(response.email);

                               });                   

                   });

                }, {perms:'read_stream,publish_stream,offline_access,read_friendlists,email'});


            });

            }

</script>
<input type="hidden" id="fbAccessTkn" name="fbAccessTkn" value="" >


Copy and paste this code on our page

call customFbLogin() function
like <a href="javascript:void(0)" onclick="customFbLogin();">facebook</a>
and change your api id
thats all it will works fine.