Right.
Just for your knowledge, and anyone else looking at this that might be wondering the same thing, here is why you needed a jail:
FreeNAS is an APPLIANCE, meaning, that even though FreeBSD is the underlying operating system, it is cut to the bone, with (more or less---this is sort of a lie) only those services necessary to run a FreeNAS server appliance. Anything that would take up space, or slow down the system, and does not have anything to do with FreeNAS, is gone. In short, as is, FreeNAS cannot be used as FreeBSD. You can't even get "man" pages (these are the help files for Unix/Linux commands). And even if you could, any CHANGES you'd make, any SOFTWARE you'd install, would be gone (more or less--again, a possible lie with a workaround) on the next reboot.
A jail, on the other hand, is a full install of FreeBSD, and it exists in your jail root, which is presumably in your permanent storage, not in the appliance operating system storage (i.e., not the USB stick). If you choose a "portjail", you get something called the "ports package", which was more or less invented years ago by our very own jkh, which is a collection of instructions on how to install a few thousand pieces of software. You can "make" any of those software packages by issuing the "make install" stuff. BSD will then fetch your software code, "compile" it, and all that shit.
Now, once it's installed, you'll need to start the service, you'll probably need to make a change to the sysrc to make it start automatically etc. You'll need a web server, which also exists in ports, etc. These are not FreeBSD/FreeNAS problems, so we're not going to help you with those, but there will be plenty of tutorials on that with the Wordpress people. Suggest you Google search for "FreeBSD install wordpress", and see how deep the rabbit hole goes.
