Passing Data to MainWindow WPF

Question

Hello,

I have A couple Radio buttons on the MainWindow to change the Background image. it works great, here is the code

 image.Source =(ImageSource)FindResource("Fire");

Now I want to put those Radiobuttons on Page and use WPF navigation to popluate the buttons in the frame(Already done). The Frame navigates nicely. But I'm lost Since the image control located on the mainwindow how can pass data from the page to execute code to change the background image???  Any Ideas?

Thank You Rick