These are my first three steps to create a Ubuntu instance in Amazon EC2.
1) Ubuntu Official AMI's are published by user with Amazon ID '099720109477'.
after the instance get launched you can access the instance with the public DNS and the AWS pem file.
2) ssh -i awskey.pem ubuntu@ec2-01-02-03-04.compute-1.amazonaws.com
To facilitate ssh, i prefer to send my own key to the instance with ssh-copy-id. Here is the link to create your own key pair.
3)cat id_rsa.pub | ssh -i testkey.pem ubuntu@ec2-01-02-03-04.compute-1.amazonaws.com "cat>> .ssh/authorized_keys"
At this point my instance is ready, and easily accessible with my own rsa credentials.
