[General] beginner!!!

Hi, I'm trying to set up a database with freeRADIUS server and I'm getting
some doubts.
I installed freeradius-postgresql package and nothing else. I've configured
all the files like it explains in the SQL How To on FreeRADIUS wiki. So far
so good, but at this part:

"
*Setting up the RADIUS database*

First, you should create a new empty 'radius' database in SQL and a database
user with permissions to that database. You could of course call the
database and the user anything you like but you probably should stick with
'radius' for both to keep things simple.

Next up, you need to create the schema for your database. There is an SQL
script file for each SQL type in doc/examples/ in your operating system's
doc directory (or where you untar'd FreeRADIUS). On SUSE this is under
/usr/share/doc/packages/freeradius/
Create PostgreSQL Database

su - postgres
createuser radius --no-superuser --no-createdb --no-createrole -P
createdb radius --owner=radius
exit

*Note:* choose a secure password when prompted for one by the
*createuser*command.

cd /usr/share/doc/packages/freeradius/doc/examples/
psql -U radius radius < postgresql.sql

"

My silly question is, do I needo to install a postgreSQL server or the
freeradius-postgresql package already takes care of it?!
My question it's because it doesn't recognize any user ids and the
createuser command.

Thanks
--
Joana Camacho