The HELM Control Panel (v3) is installed with 2 user accounts: The Admin account and the Useradmin account.
The Admin account is used for setting up your HELM configuration, including system settings and default package options.
Admin account screen:

The Useradmin account is used for adding domains, ftp accounts, email accounts, and normal site setting changes.
Useradmin account screen:

Unless you need custom configurations or want to modify the default HELM configuration, you will want to use the Useradmin account.
To get started with HELM, simply log in as Useradmin, and start adding your domains!