To change your login email address:
Open the Account dropdown menu at the top right corner of Facebook and choose Account Settings.
Click the Edit link next to Email.
Click Add another email.
Type your new email address in the open field and click Save Changes.
You will be asked to enter your password for security purposes.
You will then be sent a confirmation email to the new email address. You will not be able to log in with the new address until it is confirmed.
Any of the email addresses associated with your account can be used as login email addresses.