How to do it...

To create a new window, follow these simple steps:

1. Open the Solution Explorer and right-click on the project node.
2. From the right-click context menu, navigate to Add | Window... as shown in the following screenshot:

3. The following Add New Item dialog will appear on the screen:

4. Make sure that the selected template is Window (WPF). Give it a name, SecondWindow.xaml, and click the Add button.
5. This will create the SecondWindow.xaml file and its associated code-behind file SecondWindow.xaml.cs in the project directory.
6. Open the XAML file (SecondWindow.xaml) and replace the entire contents with the following XAML code:

<Window x:Class="CH01.WindowDemo.SecondWindow" 
  xmlns=
    "http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    Title="Second Window" Height="200" Width="300"> 
    <Grid> 
        <TextBlock Text="Second Window Instance" 
                   HorizontalAlignment="Center" 
                   VerticalAlignment="Center" 
                   FontSize="16"/> 
    </Grid> 
</Window>

7. Now open the MainWindow.xaml file to add a button into it. Replace the entire <Grid> </Grid> block, with the following XAML code:

<Grid> 
    <Button Content="Open Second Window" 
            Height="30" Width="150" 
            Click="OnSecondWindowButtonClicked"/> 
</Grid> 

8. Now we need to add the implementation for the button-click event. Simply open the MainWindow.xaml.cs file and add the following lines of code inside the class definition:

private void OnSecondWindowButtonClicked(object sender,  
RoutedEventArgs e) 
{ 
    var window = new SecondWindow(); 
    window.Show(); 
} 

9. Now, when you run the application, you will see that the MainWindow opens on the screen, containing a button labeled Open Second Window. Clicking on this button opens the second window on the screen that has text content of Second Window Instance. Here's the screenshot for your reference: