To update your user e-mail address, log in to your account, then click on your name from the Navigation drop down on the top right hand side.
Then click on ACCOUNT INFO > USER SETTINGS
That will take you to the page where you can change your email address. Enter a new email address where the current email address is listed on the form. Then click the red UPDATE button at the bottom of the page.
The system will treat the change as if you are a new user and will send a confirmation email to your current/old email address. ONLY after you click on the link in that CONFIRMATION email will the new email address be activated - until then none of the new information has been applied to the account.
Be aware that the confirmation email loves the Spam folder :) It might need to be fished out of there. If you don't see the confirmation e-mail address in your primary Inbox folder, check all junk e-mail and spam folders to see if your e-mail provider automatically filtered it into one of those folders.