To change your email address for your HubPages account, click on the "my account" button located in the dark gray strip above and to the right.(it's by the button marked "help"). This will open the "My Hub Statistics" page.
Just below the dark gray strip at the top of the page is a light gray box. Find the column that says "Your Account" and click "Your Profile".
On the left column approximately half way down the page you will see where it says "Email". Simply enter your new email address into the box across from the word "Email", Then click on the button that says "Save Changes".