Diz que você tem que correr
# cd /usr/ports/x11/xorg
# make install clean
E no prefácio , diz
Examples starting with # indicate a command that must be invoked as the superuser in FreeBSD. You can login as root to type the command, or login as your normal account and use su(1) to gain superuser privileges.
# dd if=kern.flp of=/dev/fd0