Here is a graphical demo on when / where to hit the Reply button.
If you would like to reply to a specific person or comment, on that comment, you will see the person, date and time of the comment on the left. To the right you will see a Reply link. Click that link, to reply within a reply and that will display under the persons’ comment.
To reply to the original posters question or comment, scroll down to the bottom of the page and enter your reply.
Example: Click for bigger image.
