This article by LinuxBSDOS shows us how to configure full disk encryption in PC-BSD 10.1.

Disk partition of PC-BSD 10.1Full disk encryption is supported in the graphical installer of PC-BSD 10.1, which was released on November 16 and which I just reviewed just three days ago (see PC-BSD 10.1 review).

In this article, you’ll read how to install a default PC-BSD 10.1 system on a single hard drive with full disk encryption configured. The installation image I used is the same one I used for the review, which I transferred to a USB stick by using the dd command. You may download an installation image of PC-BSD 10.1 from here.

For this tutorial, the test computer is a recent build using a motherboard with UEFI firmware, and the target hard drive is a 500 GB unit. If you wish to follow along, boot into the installer, then click through the first few steps until you get to the step shown in Figure 1. Full disk encryption is not part of the configuration in a default installation of PC-BSD 10.1, so you’ll have to click on the Customize button.

Full article with instructions: http://www.linuxbsdos.com/2014/11/27/how-to-configure-full-disk-encryption-in-pc-bsd-10-1/