This post outlines how to create a silo structure in WordPress by implementing your primary content on pages rather than posts.

Then onward, build your site using the following strategy:

1. Put your main content on static pages

Static pages (Write / Page) let you create content that lives outside of the blog chronology.

Contrary to posts, static pages can be hierarchically arranged using page parents (to the right in the editor). Your site structure could look like this:

/
/section1
/section1/topic1
/section1/topic2
/section2
/section2/topic1
/section2/topic2

… which is the most natural way to organize a site.

Also available on this page is a plugin which will create a sidebar navigation menu of your pages.