Grab the URL of the Facebook page you'd like to display a Like Box for. This should be the absolute URL to the page, such as "http://www.facebook.com/pages/Tripod/274257254348". You can find this URL by logging into Facebook, viewing your list of "liked" pages, and clicking on it. Once you are brought to the page you'd like to use, you can find the page URL in your browser's address bar. After you have this URL, go to this module's options and enter it next to "FB Page URL".
If you do not see your Like Photos/Icons, you may need to adjust the height of the module. This can be done through the module's options.