From LedHed's Wiki
FreeBSD
pkg_add -r postgresql82-server
The package creates a 'pgsql' user account. Change to that user to finish the installation:
su -m pgsql
Initialize the database:
/usr/local/bin/initdb /usr/local/pgsql/data
Create a user:
/usr/local/bin/createuser USERNAME
Log out of the 'pgsql' user account by pressing
[CRTL]+d
or
lo
At this point the PostgreSQL daemon can be started.
/usr/local/etc/rc.d/postgresql start