in order for you to see the RadListBox control you have to make sure you have the proper references in your project. For the RadListBox you need to leverage the Telerik.Windows.Controls
To help you along, go to this documentation
to get started using the control.
You can add it in your xaml using
you can add it programmatically from the code behind using this method
RadListBox StarrysRadListBox = new RadListBox();