Navigation in a Windows Store or Windows Store app is achieved using a Frame.
A Frame can host a new page that you want to open in the main or root page and then the Frame can be displayed in the main page.
I have a page called BasicPage1 and I want to open it on a button click event handler.
The following code snippet creates a Frame and navigates to the page:
// Create a Frame for the page
var rootFrame = new Frame();
Then I set the content of the current window to the new Frame I just created, as in:
// Place the frame in the current Window and activate it
Window.Current.Content = rootFrame;