Jcomments integration allows users to comment DJ-Classifieds items with the JComments extension (free).
To enable Jcomments comments in DJ-Classifieds:
In your Joomla backend go to Components -> DJ-Classifieds -> Options -> "views" tab
Scroll down to "Advert view" section and change the "Comments" parameter to "JComments"
That's all, users can now comment under the adverts with JComments.
You will learn more about how to use the JComments from the developer's page.