How to call a function of MainPage.xaml.cs from inside Unity

I follow this instruction and member PixelEnvision said that we can call mainScript_reviewClicked() function from Unity, but how to do it ? Can you help me ?

http://forum.unity3d.com/threads/196748-URL-for-linking-to-all-apps-on-Windows-Phone-App-Store?p=1335451&viewfull=1#post1335451

Thanks.

Follow the example here: http://docs.unity3d.com/Documentation/Manual/wp8-unity-interaction.html

Basically, setup an event in your unity script, find the script, subscribe to the event in the script, do what you need to do.