Where do I get templates other than what is listed within the DW application?

Just to add to the advice you've already gotten...

I am a co-founder of Project Seven, and if you don't have the wherewithal and budget to look at our tools, be very wary of online Template sites... especially if you are not proficient at writing CSS. Before using a template, test the developer's support processes. You want to use a template from a company that will respond to your questions.

Be wary!

If you have a budget to work with, look at Project Seven's responsive CSS Templates or layout creation extensions. 

Responsive Web Design Extensions, Apps, Add-ons and Plugins for Dreamweaver

Search google.  There are plenty of templates to choose from, or if you are using a CMS like Wordpress/Joomla/etc there are plenty of templates for those as well.