Go to http://developers.facebook.com/. You must have a facebook account to set up facebook comments correctly.
Choose the Apps link.
Create a new App.
Choose a name for your app, and enter a namespace.
Fill out the App form, make sure you enter the website field or the app domain will not save.
You will need the app id later.
You also need your facebook user id, go to your profile and look for the ?id=XXXXXX in the url. If you have a username in the url instead of an id, please go to http://findmyfbid.com/ to see your user id.
Please enter your app id and facebook user id into the galleries component options.
In the gallery profile settings, please choose facebook comments in the profile "main other" and/or "lightbox other" tab.
Viewers of the gallery can now comment on each image.
To moderate the images, please go to http://developers.facebook.com/tools/comments, or you can moderate in the gallery itself, as long as you are signed into facebook, and you facebook id has been entered into the galleries component paramaters.
You can also adjust the settings in the frontend. If you add yourself as a moderator, facebook will make a notification in your facebook notification panel when a new comment is added.