MVVM (Model-View-ViewModel) Example ?

Hello, As new in WPF I'm trying to understand the MVVM (Model-View-ViewModel). I came from winform. I had looked in microsoft website, but their decription of the model are so theorical that I don't understand what I shoud do in a real life scenario.
I not make complex app, but I would improve myself; anyone have an simple example to show how things should do?