Here you can create a Guestbook to let people share their opinion about your site. To insert a guestbook, go to Insert [1] ribbon and click on Guestbook [2].
You can select the email address where you'd like to receive notifications, by default is the account email address, you can choose if you want to see the entries to approve them or not, and you can change the Sign Guestbook Button.
You can remove entries at any time from your guest book, go to Setting, Entries and pres the button for the unwanted comment.