To manage your web hosting package, like email addresses and FTP users, you need to log in to your control panel.
You can do this by clicking on "My account", and logging in to the web site.
Next click on "My Services -> My Hostings", and click "View" at the hosting you want.
On the detail screen, click on "Options".
Now Click on: "Go to Control Panel"
Log in using your hosting login information.