When you go to add an Element in a Content Layout Section, the Element dialog opens in a new tab called Layout Elements. This is where you will find the Comments Element. This is a simple Element, which allows you to place the comment section anywhere in a Content Layout Section in any Layout. This would most commonly be used in a Single Post layout.
The Comments Element includes any comments made, and the Leave A Comment section, allowing people to make a comment. It will not display if comments are not allowed for that post or page.
The Comments Element can be placed anywhere in your Layout, and will dynamically pull the Comments area into the page, based on the Conditions set in the Layout. You can also use the full range of Design Elements when building your Layout.
See below for an example of the Comments Element on a post on the Fitness Demo. Follow this link for a live example.