fb_event.js

// ...
  events: {
    'click .facebook-share' : 'postToFeed',
  },

  postToFeed: function() {
    FB.init({appId: fb_app_id, status: true, cookie: true});

    // calling the API ...
    var obj = {
      method: 'feed',
      link: 'http://www.google.com',
      picture: 'http://athena.cornell.edu/images/rovers/rover_sundial.jpg',
      name: 'My text about ' + this.model.get('something_interesting'),
      caption: '',
      description: 'Sweet! This is so great and about something interesting!',
      redirect_uri: 'your redirect URI'
    };

    var self = this;
    FB.ui(obj, function(response) {
      self.callback(response);
    });
  },

  callback: function(response) {
    // callback where you do something with the response
  }

// ...
  var fb_app_id = 'your facebook application id';
// ...