If you have your user account login details at hand, you need to do the following:
Log in to your account and go to the "User settings" page. Enter your new email address in the appropriate field and press the gray "Update" button a bit further down the page. An email will be sent to both your old and your new address. In the email to the new address there is a link which you need to click before the address change takes place.
I have changed my email address and need to update my user account with the new address
