Does anybody here use WPF using Visual C#??

I'm working on a program.. here's the code

HTML
Code:
<menu>

<MenuItem header="_Close"
                Click="Close">

</MenuItem>

</menu>
And in the Code Behind, it has

HTML
Code:
Private void MenuItem_Click(Object sender, RoutedEventArgs e) 

{

I cannot seem to make that menuitem_close close the app, any help on this would be cool, thanks in advance

I know it's gotta go in here, but can't seem to figure it out..
}