Log into your account and navigate to Settings>Account.
In the "Email addresses" section, click "+ Add new email address", type your new email address and hit "Save".
You will receive a verification email to your new email address. Please click on the "Confirm my address button".
From there, navigate again to Settings>Account. Both your old and new email addresses will be showing.
If you want to receive notifications to your new email address, select "Receive notifications" and then "Save". You can also deselect notifications to your old email address in the same way.
If you would like to remove your old email address from this account, please click "x" and confirm. Please note, if you remove your old email address, the next time you log in to your account you will need to use your new email address to log in.