This article will show you how to use my PopUp Behavior that will launch a simple Yes/No Popup and explain how it works so you will be able to tune it to your needs. This PopUp should make creating PopUps in MVVM / VM style easier by generating the PopUp for you which will save you the time of creating a View and View Model for a Popup, remove the need for complexity shown by other solutions that uses messaging / services and so forth. This also allows designers to have some control to create PopUps without waiting for the programmers to make a View and VM for them.
What HisowaSimplePopUpBehavior Do
This is the PopUp that it generates, but you can customize by modding the code or by properties on behavior.
Link to: Live Application Example