WPF (Xaml) Parent/Child TabControl and TabItem Templates - How to Name and Apply

Question

Hi. I am new to both C# and WPF.
I am currently developing an application which is to be driven by TABS instead of Menus.

How do I define multiple TabControl and associated TABItem Templates and then apply them?
 
See attached dummy screen and the code I have developed so Far.

It would be greatly appreciated if someone could help me with this as it is the same concept that I have developed in another language.

Len