How to Add the Facebook Like Box

Note! - Applicable to business pages only.

Go to Facebook Like Box  
Type in your Facebook Page URL, select other(if needed) settings and click Get Code.
Click IFRAME and copy the text that will appear below.
Log into your wordpress admin account and go to Appearance - Widgets.
In the Available Widgets section, drag and drop the Text item into the Main Sidebar section.
After releasing the mouse button the text field will expand, paste in the code and click Save.