/wp-content/plugins/
directoryThe Open Graph protocol enables any web page to become a rich object in a social graph. For instance, this is used on Facebook to allow any web page to have the same functionality as any other object on Facebook. http://ogp.me/
Open code of any page on your website. The meta tags print on head of all pages.
Add to your posts excertions and thumbnail images - these details are more important for plugin.