The free AddThis service provides social media links for web sites.  It supports floating "share" buttons for social media, as well as tools for "follow" buttons.  Then, it also provides analytics to track what pages people have shared.

After you create a free account on AddThis.com, the AddThis service can be installed on your WordPress site as a plugin.  Then, from within WordPress, you connect the plugin to your registered AddThis account. From there, all the configuration of your AddThis buttons and tools will occur on your AddThis Dashboard, not in WordPress; it will automatically update on your site from there.

The video below shows two methods of installing AddThis on a WordPress site. I recommend using the plugin instead of adding custom code to your site's theme, as the code may break next time WordPress updates your theme. The video is from the AddThis Academy page on How to Install the AddThis Plugin on WordPress.