You can update existing records through your personal My Dashboard screen.  To access your dashboard you can do the following: 

Step 1: If you haven't done so already, log in or create an account. 

Step 2: After you have logged in click on My Dashboard navigatioal option seen on the left side of the screen (on desktop) or by clicking the hamburger-menu (on mobile)

On the My Dashboard screen you'll see different sections representing the record types you can manage. Open the section that corresponds to your task.