Make sure you are logged in and click on your username in the top-right menu. Click on Account Details.
You will see a field titled 'Email'. Click the yellow 'Change' button beside your email address, change your password and click 'Save'. You will also have to click 'Save' when you are taken back to the Account Details page.
You will be send an email to your new email address.Please click on the provided link to confirm email change.