How to add google tag manager inside head and body?

[Curious-Aria]

I’m using magefan google tag manager extension, but i already got gtm script in my store, i want to know the correct way to put the gtm code inside the extension, like inside head or body, so nothing breaks and tags works fine. anyone done this before? what’s the safest way to implement without double tracking? i want to keep my existing tags and still use magefan extension.