Adset Code – HD Quiz

Hi there, I know this is a newbie question, apologies for that, I did search through the forum and also the documentation and can’t find any solution. Maybe I looked in the wrong place.
Anyway, I know theres an option to put Ads between every 5th question with an Adset code, I have no idea what this is or where to look to find a tutorial. My apologies if I missed something obvious.
Thanks in advance