Visit Klout’s homepage and simply click either the “Sign in with Twitter” or “Sign in with Facebook” buttons. Klout currently uses Facebook and Twitter as the base of your account and we’re looking into supporting other social networks as the base of the Klout account for the future.
As for now, you must have a Twitter or Facebook to sign up. You will be asked to authorize Klout to read your social network data and you’ll be presented with the option to add other accounts including Twitter, Google +, and more to Klout. Once you’ve completed registration with Klout, a Score will generate for you in about 48 hours.