To use facebook comments integrated to your own site.
Need a facebook application for your site(domain).
For example:
Fill in the blank and click get code from https://developers.facebook.com/docs/reference/plugins/comments/
Then just paste that code to your site(page).
Facebook doesn't explain how the Social Ranking works, but I checked some real-world examples and I guess basically we can consider it sort by like counts.
Put this meta tag in the html.
<meta property="fb:admins" content="{YOUR_FACEBOOK_USER_ID}" />
Then if you log in with the owner of the application, you can access this url to control comments:
http://developers.facebook.com/tools/comments
or you can do it inside the Comments Box directly.
There're Moderate dropdown to Hide comment, Ban User or Boost comment. In the Settings page you have other options like add moderators or set blacklisted words, etc.
Remember to check all the FAQ on the reference docs, very useful. I wonder why those go to the FAQ though.
https://developers.facebook.com/docs/reference/plugins/comments/