I - Send Standard Events :

1. Step 1: Sign in to your Google Tag Manager account.
2. Step 2: Select your website's container and click Add a new tag.
3. Step 3: Click Custom HTML Tag and type a name for your tag.
4. Step 4: Go to FB Ads > Events Manager and click Details for your pixel.
5. Step 5: Click Set Up and select Manually Install the Code Yourself.
6. Step 6: Copy the entire pixel base code (2)
7. Step 7: Return to Google Tag Manager and paste the code in the HTML container.
8. Step 8: Click Advanced Settings > under Tag firing options, select Once per page
9. Step 9: Under Fire On, select All Pages.
10. Step 10. Click Create Tag.