You can submit a chapter of your book which they send to their mailing list of potential readers of your book. (theadwordsguy.com)
It will show you how to start email list building and engage with potential readers of your books. (paulawynne.com)
The From the Author section is your last chance to reach potential readers on a personal level, tell them why you wrote the book and how it will help them. (myworkfromhomemoney.com)