The Shareaholic plugin for WordPress provides an easy, free, way to add social share buttons to your web site.  This video explains how to use it.

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It also offers analytics and related posts, but these are not covered in this video.

This is where you can get the Shareaholic plugin: https://wordpress.org/plugins/shareaholic/

This is my post (mentioned in the video) on how to install a plugin onto WordPress: https://geckogullywebsites.com/add-plugin-wordpress-site/