Don't worry if he doesnt even knows who you are. He probably talked trash because he was behind a TV and not in your face. So he can get away with it, maybe he doesn't even want to fight you he just wants to look tough through the Xbox with some guy he doesnt even know .If he does know who you are and he really does want to fight you then you could.... Learn how to fight , but still try to avoid fighting him unless he pushes you , punches you or provokes you.