Sorry about that! Layered PDFs aren't always intuitive to use. I recommend checking out any of my free models (Hovel, Coach House, Observatory, Free Cargo Pods) to see how my layered PDFs work.
To get full use of my layered PDFs, you'll need to use the free program Adobe Acrobat Reader.
When the layered PDF opens, locate the Layers Palette (might look like a "paper stack" icon). When you open the Layers Palette, you'll see the optional graphics layers available.
Hope that helps!