There are multiple page templates available with different layouts.
This page template has no left nav, but has a right sidebar for widgets
This page template goes from left to right with no left nav or right sidebar.
This template has the left navigation, main content in center and a right sidebar for Widgets and a gallerys
Subnav on left, main content on right
How does the nav work on this page
The left navigation displays the parent/child pages of the current page. So here Page Templates is the parent, and each sub page is a child.