Once you log in to your account, click on 'My Account' from the icon on the top right of the page.

You can click on 'Edit' under Contact Information on that page or by going to the left navigation menu and clicking on 'Account Information' (under Dashboard). You can then change your email, (as well as the password, name on the account, and enable/disable remote shopping assistance). 

Please note you will not be able to amend the email address for an order that has already been placed.