Update, May 2015: The old Like Box is no longer being supported as of June 23rd, 2015. You can read more about the new instructions for the Page Plugin on the Facebook website.
Today’s tutorial is all about how to add a Facebook Like Box to your website. This presumes you have a Facebook Page already set up, and that you have Administrator privileges to manage the Page.
Step one is log into https://developers.facebook.com. Go Apps > Create A New App.
Fill out the info for Display Name, Contact Email, and select Category > Apps For Pages. The Namespace field is optional.
Go to https://developers.facebook.com/docs/plugins/like-box-for-pages/. Fill in the URL of your specific Facebook Page. Add height and width, and select either light or dark color scheme. The minimum width is 292 pixels.
On the Status and Review page, set your App status to Public. Congratulations, you have added a Facebook Like Box to your site.
If you want to manually add settings to the embed code, the HTML5 data API is on the Like Box page. You can add, subtract, or adjust these settings in the embed code where you want your Like Box to appear.
Sometimes Facebook Posts do not appear on your Like Box due to settings on your Facebook Page.
To fix this, make sure you have the following settings: Country Restrictions > visible to everyone and Post Visibility > Posts to Page appear on page Timeline.