MSDN:

Windows Phone应用程序基于Silverlight页面模型，用户可以在其中浏览不同的内容屏幕.以下主题概述了此模型，并描述了如何实现导航.此外，它们提供了以编程方式处理方向变化的指导和步骤.

看看:
Windows Phone的框架和页面导航 [如何:在Windows Phone上执行页面导航 [

MSDN:

Windows Phone applications are based on a Silverlight page model where users can navigate forward through different screens of content. The following topics provide an overview of this model and describe how to implement navigation. Also, they provide guidance and steps for handling orientation changes programmatically.

Have a look at:
Frame and Page Navigation for Windows Phone[^]
How to: Perform Page Navigation on Windows Phone[^]

Best regards
Espen Harlinn