Go to the My Account page. (On top of the screen, tap the gear icon on mobile or 'My Account').
In the account info and preferences page, click 'Change Email'. You'll be sent to the log in page where you'll be asked to log in to confirm you're authorized.
Login. If you do not remember your password, then click 'forgot password' and proceed with the process to reset your password using your old email address. If you don't remember your password and you don't have access to your old email address anymore, then you need to contact the webmaster for help.
After you log in, you'll be presented with the email change form.
Enter your password and your new email address (twice for the new email).
DO NOT CLOSE THE PAGE.
The system will send you a code to your new email address to confirm it's a valid one.
Check your email for the code, copy it and enter it into the form asking for the code.
Once you enter the correct code, your email address will be updated in the database and you should be returned to the site.