You can add comments to projects, stages, or tasks when collaborating with other users. To make collaboration easier, you can use mentions (for example, @Editor). The mentioned user (in this case, the editor) sees your comment on the Comments tab.
To add comments:
On the menu bar, click Project and select Projects.
On the Projects page, select a project.
If you want to add comments to a stage in a multi-stage project, click the Timeline tab and then click a stage.
Click the Comments tab and then click New comment.
In the New comment dialog box, enter your comment and click Post.
You can reply to a comment, edit a comment, or delete a comment using the commands from the More actions menu.