In order to use the OpenNebula integration with EC2 AWS, you need to register an account at http://aws.amazon.com/, and sign up for S3 and EC2 services.
On the main page, click on the Sign Up button at the top (it's free); you will be directed to the following screen:
If you already have an account at amazon.com (for example, if you bought books on amazon.com/.uk/.de/.it) you can use the same credentials for logging into AWS.
If you are a new user, you will be asked for personal details, and a valid credit card. In order to increase the protection of your account, you may be interested in using the AWS Multi-Factor Authentication available in both a software edition for Android/iPhone/BlackBerry, and as a hardware OTP generator (http://aws.amazon.com/mfa/).
After completing the registration process correctly, you will receive a confirmation e-mail.
Once you have received the e-mail, you may log in to AWS Management Console by clicking on the My Account/Console link...