Logon to your account as normal. Click on the 'View/Change my personal details' link and you will be taken to the page showing your account details. By the details of your e-mail address there is a link entitled 'Change my e-mail address'. Click on this link and you will go to a page requesting your new e-mail address. Enter your new e-mail address and an e-mail will be sent to this address asking for confirmation of this change to your account details. Be aware that you will be locked out of you account until you have confirmed this change. This is in order to protect the integrity of your account.