Facebook Members: THE Simplest way to bring Facebook LikeBox + Facebook Recommendation Bar functionality to WordPress. New Facebook Recommendation Bar Plugin Added to it today. Version 4.6 released today.
Follow below steps to get your Facebook App ID.
Login to Facebook and go to go to Facebook Developers.
Create a New App
Provide all required information as mentioned in below diagram.
Get latest version from WordPress Repository: http://wordpress.org/extend/plugins/facebook-members/