PostgreSQL 9.2 Log Help

I performed my first VACUUM today on my database. I'm trying to learn
PostgreSQL and learn about basic DBA tasks that need to be performed
regularly so I can eventually automate this with Cron in Linux.

I'm currently running PostgreSQL 9.2.4 on Amazon Linux (RHEL based):

Is there a way to control what gets logged in
/var/lib/pgsql9/data/pg_log/postgresql-{$DAY}.log

When I view my log for today (Wednesday) after running VACUUM on my
database, I see nothing mentioned or noted in my logs as to if this
ran / failed / passed / what the heck happened...it's like nothing is
getting logged except start up status and auth failures:

[root@db1 pg_log]# cat postgresql-Wed.log

FATAL:  password authentication failed for user "postgres"
FATAL:  password authentication failed for user "carlos"
FATAL:  password authentication failed for user "carlos"

[root@db1 pg_log]#

Can someone help me understand how things / tasks / commands get
logged in the database and where that would be?

Thanks!

--
Carlos Mennens