Facebook shares not showing on wordpress for unofficial FB buttons

Hello,
I apologize if we were supposed to post this under a specific plugin forum. But we thought it should be posted here since we actually can’t find – but would like to find out how to install – an official Facebook “share” plugin.
The problem is that ALL of our website posts have facebook shares wiped out to “0”. We figured out our current plugin (Social Share WordPress Plugin – Access Social Share) is NOT an official Facebook button. Unfortunately, Facebook retired their old API last week, which means they no longer provide sharing counts for any unofficial buttons added to a website via third party plugins (which is what we had). Basically from what we learned, the custom FB button on wordpress.com sites have stopped showing a share count and only display using the official FB button. So we would like to use the official Facebook button and not use our old unofficial FB button anymore.
We googled and found an official FB share button:https://developers.facebook.com/docs/plugins/share-button/
However, we’re confused about where to post the code on wordpress (so it applies to every post)? It’s a long code and instructions are complicated.
Any help would be appreciated.Thanks very much!

The page I need help with: [log in to see the link]