You can change your email address within 'Account Settings' which is located in the toolbar at the top of your page. When in Account Settings there is a 'Change' button next to your current email address which you need to click.
You will then be prompted to enter a new email address.
Once updated, press 'Submit'. An email will be sent to your new selected email address. You will need to verify this email by clicking the verification link within. When you have clicked the verification link, your email address will change.