facebook login to my site

the fb:login-button tag may not be what you want. I would create your own button and then use the facebook javascript Login method to login your user.

<button type="button" onclick="doLogin()">Log in Here PPL!</button>

then in a script tag

var doLogin = function() {
    FB.login(function(response) {
       if (response.authResponse) {
         //they're logged in!  we've got them!
         location='/product/sell_it_now';
       } else {
         console.log('User cancelled login or did not fully authorize.');
       }
     }, {scope: 'email'});
}

from here: https://developers.facebook.com/docs/reference/javascript/FB.login/