Facebook Event tracking will help us to understand the performance of content and track whether people are interested to share the story in facebook. Based on this report we can easily track the total number of clicks and shares which is coming from facebook traffic.

Let us know the steps of Facebook Event Tracking with Google Tag Manager :

1. Create a tag and name as facebook event tracking tag
2. Select the track type to event
3. Give the action name as per your understandings
4. Give the label name as per your needs
5. Select the default GA Variable for GA settings
6. Create a trigger and name as facebook event tracking trigger
7. Select the trigger type to Click-just links
8. Give the condition as per your requirements as Class/URL/Text/Element
9. Save both tags and triggers & then preview it and if works fine then push it to live.
10. Finally you will see the data in Real time GA reports.

Drop me a line if I can do anything else for you.