With over a 100,000 active installations this plugin is the one to have for ease of use and flexibility. Add the plugin in the widget area or drop a short code onto a page. You can set the Title, Facebook application ID, your Facebook page URL, along with other settings such as width and height.

There is a brief introductory video on the page linked below.

https://en-au.wordpress.org/plugins/facebook-pagelike-widget/