You're confused. Allow me to explain.
FreeNAS 0.7 was written and maintained by different developers. There was a shakeup within the FreeNAS project and the FreeNAS brand name was sold to iXsystems. iXsystems then wiped the slate clean and started over from scratch. All FreeNAS versions that are 8.x or newer are the "new" OS. Anyways, the old developers couldn't use the FreeNAS name since they sold it, so they changed their name to NAS4Free.
NAS4Free is technically the updated version of the old FreeNAS code your guide references. The version of FreeNAS that is used and supported on this forum is a complete rewrite of the code from scratch with different developers and different management. There is nothing in common between the old FreeNAS and the new FreeNAS aside from the name and that they are both FreeBSD based.
If you want to use that guide, you should go over to the NAS4Free website and download and use their OS(assuming the Firefly options are still in their OS). If you want to continue using the OS you have installed, you will need to setup a jail and use plugins(assuming there are plugins for what you want to do).
This is why guides can't always be relied on 100% and you should verify the guide is still valid. My guess is that the guide you have won't be 100% correct with NAS4Free(The old FreeNAS versions are more than 2 years old, so that guide is quite dated), but there is almost certainly someone who has explained how to use Firefly(again, assuming Firefly exists in NAS4Free).
Hopefully this clears everything up.