Create new ITreeNode element as a child node

Hello,

I'm trying to make a QuickFix where I create a new class with a specific name and add it as a child to the body of a given ICSharpNamespaceDeclaration.

So basically I want a quickfix that changes this: 

namespace ClassLibraryProject
{
}

Into this:

namespace ClassLibraryProject
{
    public class NewClass
    {
    }
}

I'm new to the ReSharper sdk and I'm mainly trying to follow the DevGuide and the sample files from the plugin template but the example shown there only changes the name of the node. I haven't been able to find any information on how to create new ITreeNodes so I hope anyone here knows what I can do.