<p>How do I create a new webpage in the Documentum front end Webtop?  </p>

Why WebTop?  You should use Web Publisher which is built on WebTop with the specific purpose of managing web content. Is this an OOTB installation?  Web Publisher / WebTop requires significant amount of customization in order to start being useful.  Do you have templates defined?  If so, then just go to File New and select your template.
http://www.dmdeveloper.com/
Is a good site with some very good how-to's.