To confirm your email address change (required):
Log in to the email inbox for the address you just updated.
You should see a new email from Twitter. Open it. (Search for mail from "Twitter" if you cannot find it.)
Click on the confirmation link in that email.
You should then be directed to your Twitter account. Your change is now complete!
You will also receive an email notification at your old email address - no action is needed and this is not a confirmation of the email address change, just an alert.
You can also resend the confirmation email from your Twitter account at any time by clicking the yellow link on your homepage.