I've installed it using yast, like any other program. Start it with rcpostgresql start. Documentation is
here. If you access the server from the network, you need to add a line like "host DBname username 255.255.255.255/0 md5" to /var/lib/pgsql/data/pg_hba.conf. You may manage the server using psql and pgaccess, the latter being quite buggy. Does this suffice?