PC-BSD has the Warden GUI to install and maintain jails. Setting these up can also, and I’m sure many would prefer this way, be set up from the console. Cyberciti.biz has published a useful and extensive guide:
How do I setup operating system-level virtualization that allows me to partition my FreeBSD-based server system into several independent mini-systems called jails.? I’d like to set one jail for mail and another for web server via 2 public IP address.
Each jail under FreeBSD virtual environment runs on the host machine with its own files, processes, user and superuser accounts. From within a jailed process, the environment is almost indistinguishable from a real system. The easiest way to set, create and modify jails is using a framework called ezjail.