Next to the ZIP/Postal Code field in the Starter Web Page Wizard, you will see a checkbox next to the "I'm Online" icon:

If you use Yahoo! Messenger, your visitors can click on this icon on your starter web page to send you an instant message. (When you are offline, the icon will change to display a "Not Online" message.) Select the checkbox to add the icon to your page; leave it unselected if you don't want to include it.