FreeBSD is an advanced operating system distributed under the 2-clause BSD license. The FreeBSD website has all the information needed (especially the handbook) to install and configure FreeBSD itself.
The KDE/FreeBSD website is supposed to be the definitive source of information. Additional information for developers can be found on the FreeBSD KDE SC 4 wiki.
Please see the page on building KDE SC for general instructions. See the page on building KDE SC under FreeBSD for specific information for FreeBSD.
KDE TechBase 