Log on to the Disneyland Resorts website to create a free Disneyland account for yourself. See Resources.
Enter your date of birth by choosing the month and date from drop-down menus and entering your year of birth in the appropriate field.
Provide Disneyland with your email address and create a password. Re-enter your password for verification. From here you'll provide your home address and phone number. Read the terms and conditions, click the box to accept them and submit your registration. Your birthday is now registered with Disneyland.