To change your email address, go to your profile by selecting "Your Profile" in the menu under your name on the top right of the screen:
Then on the left side of your profile, below your photo you will see a number of options under the heading "Your Settings". Click on "Email Address":
In the box that appears you will see the email address currently associated with your account. In this box you will need to:
1. Enter the new email address for your account
2. Enter your account password
3. Click "Send Confirmation"
You will get an email at this address requesting you to click a link to verify this new address. You must do this in order to complete the change.