First of all download Facebook Like Box Widget

Then install it on your website

If you don't know how to do it - then please follow the link - Installing an Extension

After installing it - go to Extensions>>Module Manager

There will be an unpublished module on top - you can either use it or create a new module

Select Module Position where you want to publish the module

Basic Options : 

Page URL : - Can create a facebook page from here - or provide your existing facebook page url. keep in mind that you have to provide facebook page url - it won't work if you provide your facebook profile url or anything similar :)

Rendering : Choose the option you want

Width : Width of Module

Height : Height of Module

Color : Choose the theme either light or dark

Border Color : If applicable

People Faces : Hide or Show - Default (Show)

Stream : Yes or No - Default (no)

Header : Hide or Show - Default (show)

Auto Language : Yes or No - Default (yes)

Language : Choose from Dropdown