Look for the Email Settings section in your profile and click the Gear Icon to edit your email address. Enter your new email address and password in the appropriate fields.
Once you're finished, click the submit button at the bottom of the page to save the changes.
After you've submitted the new email, a confirmation will be sent to the address. Be sure to open the email, click the link, or copy and paste it into your browser to confirm the changes and complete the update.