I'm kind of a recent first timer, and hopefully hes nothing like I was. Then again, I was only in like 7th grade, but anyways.

I suggest surrounding him with people he knows won't mess with him, will make him even more paranoid if hes with kids that will hit him push him fuck with him shit like that, just keep him chill.

Bring up some food, tell him to hit the blunt easy to so he doesn't cough and get scared or anything. Had a friend lay on the ground who could barley breath he hit it so hard.
Just keep him chill, I think watching movies is the most relaxing. Get some food.

As stupid as this sounds, don't get him wrecked, just give him a few hits and see how high he gets. I know kids who went nuts the first time and others who were insanely laid back.