I have a sony blue ray disc player that's 20 feet away from my pc in another room. I have a wireless router that I will hook up to my pc with a ethernet cord. Why is it called wireless if i need a cord? Also, I was told I need a usb adapter, why do I need that? Can't the blue ray talk to the router that's connected to my pc? The adapters don't cost much but I am confused about the process. Is there a book I can read?