Добавьте изображение через Facebook API

Может быть, что-то вроде этого:

var publish = {
  method: 'stream.publish',
  message: 'getting educated about Facebook Connect',
  attachment: {
    name: 'Connect',
    caption: 'The Facebook Connect JavaScript SDK',
    description: (
      'A small JavaScript library that allows you to harness ' +
      'the power of Facebook, bringing the user\'s identity, ' +
      'social graph and distribution power to your site.'
    ),
    href: 'http://fbrell.com/',
    media: [
      {
        type: 'image',
        href: 'http://fbrell.com/',
        src: 'http://fbrell.com/f8.jpg'
      }
    ],
  },
  action_links: [
    { text: 'fbrell', href: 'http://fbrell.com/' }
  ],
  user_prompt_message: 'Share your thoughts about RELL'
};

FB.ui(publish);

Вот живой пример: http://fbrell.com/fb.ui/stream.publish