Originally Posted by
Jiri Matejka It's not enough to copy the XAP, it must be deployed using Windows Phone Application Deployment tool (or from Store of course), which is a part of Windows Phone SDK. You must register your phone as a Developer one to do that. See details here:
How to deploy and run an app for Windows Phone 8 That's true if he downloaded some ripped XAP file from any source other than the Windows Phone Web Store. In this case I wouldn't even tell him how to correctly deploy, install and run it, tbh. But if he got the XAP from the web store, he just needs to copy or move it over to the root folder of his device. When he now opens the store on his device and pulls up the bottom app bar, it should show an option called "install local files" or so. Tapping on that should display a list of all found XAPs. Tapping on one of these will install the game or app. If the device meets the requirements and - in case of a paid app - he purchased the app beforehand.