Older versions of FreeBSD use XFree86 as their X11 software, but due to licensing and update issues, XFree86 has been replaced with Xorg as of FreeBSD 5.3-RELEASE.
To install Xorg from source it is recommended that you first update your ports using cvsup.
Log in and su to root:
and you have 2 options. You can build from ports or use the pre-built FreeBSD Packages.
Note: To build Xorg in its entirety, be sure to have at least 4 GB of free space available.
To build Xorg from ports:
# cd /usr/ports/x11/xorg && make install clean
To add the BSD package:
# pkg_add -r xorg
After you have installed Xorg, you must configure it. This is a multi-step process and can get a tad complex.
As su, run the Xorg Config File creator
# Xorg -configure
This will generate an X11 configuration skeleton file in the /root directory called xorg.conf.new (whether you su(1) or do a direct login affects the inherited supervisor $HOME directory variable). For XFree86, this configuration file is called XF86Config.new. The X11 program will attempt to probe the graphics hardware on the system and write a configuration file to load the proper drivers for the detected hardware on the target system.
This will run a sort of wizard that will simplify the process for creating the config file.
The next step is to test the existing configuration to verify that Xorg can work with the graphics hardware on the target system. To perform this task, type:
# Xorg -config xorg.conf.new
If a black and grey grid and an X mouse cursor appear, the configuration was successful. To exit the test, just press Ctrl+Alt+Backspace simultaneously.
Note: Most of this information came from the FreeBSD Handbook located http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/x-install.html