Tree View: "Expand All" and "Collapse All" functionality to show/hide content

How does MSDN program the main frame to "Expand All" and "Collapse All" the content?

How do they get the content into the Tree View?

Is this even using Tree View Class to do this?

Here is a link to the TreeViewClass:
http://msdn2.microsoft.com/en-us/library/system.web.ui.webcontrols.treeview.aspx

I figured out how to pull a treeview from a database, but can't figure out how to get the page content into the leaf nodes.

Thanks,
Dan