To add a Facebook feed, you will first need to set up a Facebook App connection.
Here is how to add a Social block to your page:
1. Select Content
2. Select the Page you want to add a social feed to
3. Select the green + button between content blocks
4. Select the Feed field and select from your currently active Facebook pages. Limit sets the amount of posts on your page.
Note: It may take an hour or so for Facebook posts to start showing up.