If the option Enable discussions in User Portal Settings is on, learners have the ability to add comments to their assignments. The Account Owner, Administrators, and Publishers can view, reply, edit, and delete users' comments from their site panel.
To add a comment to a course, go to the Comments tab on the Manage course page.
On this page, you can leave a comment on the selected item. A user can add, edit, delete his own posts, reply to other posts, add links and up to 10 file attachments to each post.
To view the comments summary, open the Discussions tab in the main menu.