I ran into a few errors and a number of people have reported problems in the comments page on Piotr's site. I'm hoping there will be an update soon. But I'm kind of working on my own system now anyway which works in a slightly different way.
In the meantime you can still use the default Navigation system, every time you add a Page you can tick "add to main menu" so it's pretty easy. Look at the Menu.cshtml and MenuItem.cshtml files in Orchard.Core/Shapes/Views if you need to customise the rendering.
You could also just query the ContentManager in your view with:
But you'll need to gain some understanding of how content items work and how you can pull out the correct data (RoutablePart). You should probably work through the "hello world" module tutorial and look at some other modules code first to learn how it all