Postgresql 101

[Emmanuel Seyman <seyman ediciel com>]

Hey all.

After years of using MySQL, I've decided to learn PostgreSQL and
I'm having a little trouble.

I've installed the all the postgresql rpms on my RHL 9 machine and
I've run the command "service postgresql start". My question is:

What do I do now?

The postgresql doc say that you have to run the initdb command but
it looks like this was done when I started the service the first time.
How do I log in a database?
What is the password to su to postgres?
Do the createdb and createuser programs do anything other than output
error messages?

Somebody, help!!

Emmanuel