Head to My Account >> Under Profiles, select your name

From here you can edit information such as the email address you use to login to your account, the password you use to login with, your birthday, contact information and any other profile details you've been asked to input during sign-up.

In My Account >> Under your name, you will be able to update information that was previously filled out for any of your forms.

Just click Edit next to the desired field, make the necessary changes and then click Save.