In order to install fantastico from WHM you need to login to WHM of that server as root:
WHM -> Add-Ons -> Fantastico De Luxe WHM Admin (scroll down the left menu).
Upon loading, Fantastico De Luxe WHM Admin will auto-update your existing installation (if existing). All admin files (masterfiles, tarballs, settings etc) will be moved to or created at /var/netenberg.
After the installation is complete, click on “Settings” and go through the settings. While some settings are not important, some other (marked below with an *%2