Register for a Docker ID
Your Docker ID becomes your user name space for hosted Docker services and becomes your username on the Docker Forums.
Go to the Docker Cloud sign up page.
Enter a username that will become your Docker ID.
Your Docker ID must be between 4 and 30 characters long, and can only contain numbers and lowercase letters.
Enter a unique, valid email address.
Enter a password between 6 and 128 characters long.
Click Sign Up.
Docker sends a verification email to the address you provided.
Click the link in the email to verify your address.
Note: You cannot log in with your Docker ID until you verify your email address.