Here's how to highlight any text in the e-book section, and write a comment:
Select the text you want to highlight and click the Annotate Adder
icon from the pop-up
Select any of the color in which you want your text to be highlighted, add comments, links, media title, upload file, and add tags. Click the Save
Hover on the highlighted text, a pop-up will appear on which you can see your comments.
To edit the annotated text, click the edit
icon and save it again. To delete the annotated text, click the cross
icon on the top-right corner of the pop-up.