To change the password, please go to "My Account" (above right). In the account menu, click on "Information" and enter your new password under "Password" and then click Save.
If you have forgotten your password you can click on "My Account". It opens a new page on the bottom left "Forgot your password?" see. This link takes you to the next page where you have to enter your e-mail. Then you will receive an email with a password which you should change after login.