I'm new to Sitefinity and building templates in Visual Studio. What I'm trying to do is build a template that will have reusable components included automatically (ie. header, navigation, footer, etc). This way, when a content editor goes in to add an item, he won't have to manually add all of the elements that should already be on every page.
How can I add the navigation widget to the template I'm building in Visual Studio?
Templates are better created in the Page Templates under the Design menu of the Sitefinity Administration Backend.
You can create a single master page in Visual Studio for the very basic layout, then use the Page Templates to base a template on that master page. You can then add the elements (navigation, footer, etc) to those templates, and create pages based on those templates.
You can even nest the templates so that you have the base (using only the master page) then a two-column, three-column, etc layouts.
Here's a video with some more information on page templates: http://www.sitefinity.com/documentation/gettingstarted/design/create-your-first-sitefinity-template
I hope this is helpful!