Once you've signed in, you'll see several options at the top of your screen:
Update Personal Info
Update Credit Card
My Downloads (use this to download your product once it's available)
Just click the option that corresponds with what you need to update and follow the on-screen instructions. If your account looks good and there isn't anything you need to change, that's it! You're done and you have confirmed your order for processing.
Important: If you do receive an additional email reminder to update your credit card or account, but you have already done so, please disregard it. Your name may not have been removed from the mailing list before it was sent. Your account is still up-to-date with whatever changes you made.