WPF stackpanel

First thing is to handle the event, in WPF you can use the C# code to handle all of the events in your application. Such as button click events, in Visual Studio if you write the Click="" in XAML the Visual Studio would automatically create another function in your code-behind, as 


void Button_Click(object sender, EventArgs e) {
   // this is the code block for handling the event
}


Inside the block, you can use the logic to show the previous Grid. In WPF you can easily name your controls, suppose you're having two controls for Grid, and you name them like Grid1 and Grid2. Inside that button click event you can change their Visibility property, to display either one depending on your logic. For example, if you want to display Grid1, you would write this code, 


// View Grid1
Grid1.Visibility = Visibility.Visible;
// Hide Grid2
Grid2.Visibility = Visibility.Collapsed;


This would do your job for you. You can read the MSDN document for the Visibility property of the controls.