How to set Facebook Ads in groups

How to set Facebook Ads in groups

I read Facebook has a pilot and they want to make it possible to put Ads on groups
but where i can find how to do that ? i want to try something
https://techcrunch.com/2016/10/10/facebook-group-ads/

also i guess it can be done, i saw myself some ads in groups which i am joined on

thanks

plz someone maybe knows ?

These ads are placed by Facebook not the owners of pages or groups ..