As always, log in to your account. Then, select "My Account," and then, "Preferences." Click on "Email Addresses."
You'll see a list of the e-mail addresses associated with your account. To add an email, select "Add an Email," type in the new address, and select "Submit." You will receive a confirmation email at that address.
If you want to remove an e-mail address, simply click on the gear icon to the right of the e-mail address you want to remove and select "Remove Address."