[Q] Giving applications ARM support for Winodws RT topic

I'm simply inquiring about how to make a x86 application into an ARM compatible application. I've acquired the source code of an old game, Lugaru, just to practice this. What would I need to start off with doing? I'm having trouble uploading, so you can download the source here: "https://code.google.com/p/lugaru/downloads/list". I have no experience in C or C++, only Java.