Ports Tree, Installing
Before you can install any ports in FreeBSD you will need to install the ports collection. The ports tree is placed in /usr/ports/ and consists of the makefiles and information required to properly download and install all of the FreeBSD ports.
The easiest way to install the ports tree is to use sysinstall
> su (enter root password) > sysinstall (or /stand/sysinstall for versions < 5.2) -> Select Configure -> Select Distributions -> Select ports -> go to OK -> Select installation media, (CDROM, FTP, ...) -> go to Exit -> Exit sysinstall (Press X)
You can also go to FreeBSD.org and ftp the latest ports.tar.gz (about 200megs or so,) and uncompress it in /usr. But why do it manually when you've got sysinstall to deal with the hassle for you?