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.

Setup FreeBSD Jail with ezjail