Once you have logged in, click the "My Account" drop-down menu in the top right corner of the site. In the "My profile" section you can change your password. Then click on "Enter".
If you have forgotten your password and are unable to log in, click "Log in" at the top right of the site. Then click on "Forgotten password". Enter the email address for your account. A password recovery email will be sent to you. Check your Spam, Junk or Promotions tab if you do not see the message in your inbox.