In Step 9 you can tell all about it, add images, paste the guestbook html code or any code you have that goes in the body of the page.
To start a new line use <br>
To start a new paragraph use <p>
For more html codes go here
The most common mistake is to add a body tag in this block, or any html code that belongs to the top of the page before the body tags. Adding a body tag to this block is the same as if starting another page inside a page.