This page is the top-level page devoted to information for volunteers. Build the hierarchy below it as you see fit (WordPress allows you to assign a Parent to every page and give every page an Order.
Use the Jenson Pages option under the Page menu in WordPress for a good a birds-eye view of your site structure, page order, and hierarchy. From there is is easy to edit pages as well as see their permalinks so you can link page-to-page within your site. When you link to another page on your site, keep it in the same tab / window. When you link to a document such as a PDF, or when you link to another site, it is best to have the link open in a new tab / window.
As you add pages to this section and move them around, the menu to the left will change automatically. In this way you can build the structure of your choosing and can change it easily as your site evolves. See http://sarsef.org/volunteers for an example of their Volunteers section.