In order to use Facebook comments on your site you will need to create a Facebook app. If you have previously created an app for your site, then you can use that app ID. Otherwise, you will need to create a new app. For more information please read the help documentation (Theme Settings->Facebook Comments).
1) To get started, visit the Facebook Comments Moderation Tool page.
2) You will go to the comments moderation page. You can moderate the comments from this page.
3) You can change the comment settings, add new moderators etc. from the settings page.