The Register window allows you to enter your personal registration number. To get your number, see the Registration section. Each name has a unique registration number, so be sure you enter your name exactly as indicated on the registration form. The name is case-sensitive. Names usually have the first letter of each name uppercase and the rest of the letters lowercase.
To view the Register window, select the "Register!" menu item. Then select the "Enter Code" button on the lower left of the window.