You want to create users and restrict rights in the GFI LanGuard main application, not in Central Management Console.
The current version of the GFI LanGuard does not have a feature for adding separate user accounts for the LanGuard main application. It will run under the service account specified for the GFI LanGuard attendant service when installing the program. This service account can always be changed by navigating to services, selecting the properties of the GFI LanGuard 12 Attendant service, and specifying the user to log on on the appropriate tab.
To request this as a possible feature in future versions of the product, you can submit a feature request directly to the product management group.