Steps
Click the person icon at the top right of the home page:
You will now be on the My settings page. Within the Details box your e-mail address will be listed - click on the button marked Change located to the right of the Change password button.
Enter a new email address and then click on the Save button.
Your e-mail address will be changed immediately and should now be used when logging in in the future.
You will also receive an e-mail alert to your old email address to warn you that the e-mail address was changed.