Add a new widget or edit an existing widget to open the Edit Widget dialog. Find and click on Commenting in list of menus at the left.
Note: The Commenting menu is not available to every widget.
Use the Commenting menu to add a comments stream to a widget. To turn on commenting, check the Enable Comments box. This will add a link to the widget that, when clicked, displays a dialog box with all comments and a field to leave a comment.
Number of Comments to Show
Number of comments to show at once.
The label for the comments button that appears in the widget. The default label is Comments.
Show Comments Count
When enabled, this shows the number of existing comments so that visitors can see if there are existing comments to read without having to click the button.
To learn about moderating comments, please see the Comments Widget.
Getting a Vanity URL for your Facebook Page
Facebook keeps comments grouped into a single plugin by requiring a unique URL for each plugin. We use the URL to your custom app as part of this, which means that if you have a generic, Facebook-generated Page URL and later create a vanity URL for your Page (for example, facebook.com/MyCompanyPage), your Comments widgets URLs will change, causing old comments to disappear. For this reason, you may want to avoid using any commenting until you get your vanity URL.