link found here. You'll also have to answer three Call of Duty trivia questions. Yeah, go figure.
This round is just for players in the United States, but international players can take heart. Infinity Ward has announced that the beta will also be available in Canada, Austria, Belgium, Denmark, Finland, France, Germany, Ireland, Italy, Norway, Netherlands, Portugal, Spain, Sweden, Switzerland, United Kingdom, Australia and New Zealand. Details will be announced soon, so keep an eye on the site for more details.