In order for you to update your email address you just have to follow the steps below.
On the top rand hand side of the dashboard, you will see an icon with a silhouetted face and an arrow next to it pointing down.
If you click on the arrow, a drop down list will appear with the options Profile, Upgrade Plan, and Settings.
Click on Profile. A new screen will appear. On the bottom of this new page there is a field where appears the email you want to replace.
Complete the field with the email you want to add.
Once completed, click the "Update my profile" button to complete the request.