As a contest participant, you can change your own password through the password reset link at the contest site.
The password reset link can be located by clicking the Sign In button at the upper right-hand corner of the Home page of the contest site.
Click the Forgot Your Password? link below the Sign In button (see red box):
You will be taken to a screen asking for your email address. From there, a temporary password reset link will be sent to your email inbox.
You will need to click on the link in the email to set your new password.
NOTE: The temporary password reset link expires after 60 minutes. If you click the link after 60 minutes has lapsed, you will be taken to a screen to request a new password reset link.