If you’d like to add comments, first you’ll need to make sure the Collaboration Panel is open in the right sidebar. When this panel is open, you’ll automatically see the comment option appear above any text you’ve highlighted.
Open the Collaboration Panel in the right sidebar
Highlight the text you want to comment on
Click the comment button that appears above the highlighted text.
Type in your comment in the text box
and click the green Comment button or pressCTRL/CMD + Shift + Enterto save.