To leave a comment, scroll to the bottom of your page. Between the page content and the navigation links at the bottom, there is a box that says “write a comment”.
Click in that box.
This will expand a full comments box with a standard set of word processing tools. In your comment, you can choose between a number of font sizes, bold/italic/underline, text colors, bullet points, alignment, links, tables, and attachments.
Type your comment, add whatever formatting or other elements you wish, then click either Preview, to see how your comment will appear, or Save to post your comment.