To create a page, point your browser to http://www.facebook.com/pages/create.php
CometChat does not allow use of Facebook Groups. You must create a Facebook Fan Page.
On creation of a Facebook Fan Page, click on the Settings tab on your Facebook Fan Page and click on Page Info on the left panel.
Now go to: CometChat Administration Panel –> Features –> Other Features and click on the Configure icon besides the name.
Enter your Facebook Fan Page URL in the box and click on the Update Settings button.