Assuming you're talking about chainging your email address on MMOsite, follow these steps:

1) Make sure you're signed in. :P
2) After you sign in, head to the home page and click on "My Profile" found in the top left corner of your browser.
3) After you're at your profile page, scroll over "MY MMOSITE" icon (looks like a little kid with a thumbs up) and click on "Modify My Information".
4) Under the "My Profile" tab, you can input all of your personal information. Including your email. That's where you type in the new email you want and then click on "modify" which happens to be right next to it.
5) Afterwards, you will get a confirmation email, check the inbox of your email (and possible junkbox too, if not found in inbox) and click on the confirmation link. And Viola! You are done.

Hope this has helped you.