how close window from buttom inside content template

Hi guys
In the App.xaml have a style for window to define the
title bar and border of all window in my app.

It look like I want, also have a button to close the window
but i dont know how to close the window.

if i make
  <Button Click="Button_Click"  Content="X" >
 
 in the event handler inside App.xaml.cs
 I dont know how get reference to the window
 
 private void Button_Click(object sender, RoutedEventArgs e)
        {
            referencewindow.Close();
        }

 also need to write drag event to move the window.
 is the correct aproach or mus to try with command binding?
 Any body, know how to do it