In WinRT api, how to accept user input in a dialog just like in Weather and Finance apps

I am trying to display a dialog that allows the user to type a location, just like in the "add places" function of the Weather App on Windows 8.

Windows.UI.Popups namespace does not have an appropriate control. It has the MessageDialog, but I don't think it can be customised to include a textbox in it.

Would I need to use Windows.UI.XAML.Controls.Primitives.Popup control by any chance?