This tutorial by user CWharton shows us how to get PostgreSQL set up on FreeBSD. Follow the link below for the full set of instructions, as well as a discussion by users on /r/freebsd.
PostgreSQL is a powerful, open source object-relational database with over two decades of continuous development. It is one of my favorite databases because of it’s community, functionality, and extendability. FreeBSD with built in ZFS support, jails, and several other feature is a great platfom to host your PostgreSQL instance.
At the time of this write up the latest version of PostgreSQL is 9.6 but you are not required to install the latest version. FreeBSD support several version of PostgreSQL. Simply search for all the latest versions and choose the one that your project supports.