Facebook APP ID code injection

Hi, I´ve been trying to activate my commerce account on Facebook and apparently my website is bugged according to them with the below message:

The following required properties are missing: fb:app_id

My pixel is working fine. I have already created my facebook app to link to the website with the app id number, as they required me to do so, but I don´t know how to inject the code. Can anyone help me out please?

Thank you so much.