Comments are managed through a dedicated page in your Control Panel. You'll find it's very similar to editing entries or categories in Craft.
The left-hand sidebar groups all comments by the element they were made on.
You can filter the right-hand side table as you need to. It's especially useful to filter by a comments status. You can also use the checkboxes on each row to update multiple comment's status at once.
Clicking on the first column will take you to the a page where you can edit a comment. Here you can view all information regarding the comment, such as date, URL, IP Address, User Agent and more.
You are able to change a comment's text and status from this page.
Available for Craft 2 for free, Craft 3 coming soon for $49.