<p>You'll get brochures in the mail that explains most of the process. But if you're too lasy...
<a href="http://www.campuslife.cornell.edu/campuslife/housing/upload/HousingLotteryRoomSelection08-web.pdf%5B/url%5D">http://www.campuslife.cornell.edu/campuslife/housing/upload/HousingLotteryRoomSelection08-web.pdf</a></p>