No worries ... did you find any document that comes with the ports package
regarding installing postgres the BSD way?
If not: as which user did you do the initdb?
The "traditional" way (built from source, and the way I use
postgres on Slackware) does this:
chown postgres /usr/local/pgsql/data
su - postgres
/usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
/usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data >logfile 2>&1 &
In other words, you're asked to create the user account first, and
then run initdb as that postgres user.