problem with accessing or creating a database..

Hi,

I've installed the new Postgresql 8 Beta 5 on my webserver
but I can't create or access a database.

When I just type pgsql in the Linux bash I'll get the following error:
psql: FATAL:  database "root" does not exist

Ok then I tried to access the template1 database and
here I'll get always the following error:

psql: FATAL:  user "root" does not exist

How do I create a new user account so I can access, create
new databases with it ?!?

I didn't find anything about that in the documentation or
maybe I've missed it...

THX anyway..