Enabling A Comments Template

I just created a comments.php template and copied the code from the default Kubrick theme into the template.

I have this code “<?php comments_template(); ?>”, but I am not sure where I should place it. I have seen it inserted in a single.php template, but I have no idea what the use of the single.php is for?

Any help in clearing things up and having my comments made viewable on my blog?