Thanks to these users for the various guides on setting up different desktop environments on FreeBSD.
KDE on FreeBSD 10.2 by sk –
http://www.ostechnix.com/how-to-install-kde-in-freebsd-10-2/
KDE on FreeBSD 11 by
http://fosskb.in/2016/02/17/installing-kde-4-desktop-on-freebsd-11/
MATE on FreeBSD 10.2 by sk –
http://www.ostechnix.com/install-mate-desktop-freebsd-10-2/
MATE on FreeBSD 11 by Johnson D –
http://vpierre.it/installing-mate-desktop-on-freebsd-11/
GNOME on FreeBSD 10.2 by sk –
http://www.ostechnix.com/install-gnome-desktop-environment-in-freebsd-10-2/