Postgresql refure to connect

[Giuseppe Sacco <gsacco@hsomail.com>]

Hi,
I have just installed the postgresql DBMS from debian hamm.
I am trying to play a little with it, but at the first attempt I get this
error:

hsogso:~# psql
Connection to database 'template1' failed.
FATAL 1:  SetUserId: user "root" is not in "pg_shadow"
hsogso:~# uname -a
Linux hsogso 2.1.120 #16 Wed Sep 9 14:36:32 CEST 1998 i586 unknown
hsogso:~#

Where do I create postgres users? I checked that the standard configuration
should permit everyone to connect. But I didn't find anything about pg_shadow.
What is it?

And then, after reboot I cannot start the server:
hsogso:/tmp# /etc/init.d/postgresql start
Starting PostgreSQL postmaster
FATAL: StreamServerPort: bind() failed: errno=13
        Is another postmaster already running on that port?
        If not, remove socket node (/tmp/.s.PGSQL.<portnr>)and retry.
/usr/lib/postgresql/bin/postmaster: cannot create UNIX stream port
hsogso:/tmp# ls -la /tmp
total 4
drwxr-xr-x   3 root     root         1024 Sep 16 00:21 .
drwxr-xr-x  21 root     root         1024 Sep  6 10:36 ..
-r--r--r--   1 root     root           11 Sep 16 00:21 .X0-lock
drwxrwxrwt   2 root     root         1024 Sep 16 00:21 .X11-unix
hsogso:/tmp#

And, if I execute "strace postmaster start", then I get this final output:

298   socket(PF_UNIX, SOCK_STREAM, 0)   = 4
298   setsockopt(4, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
298   bind(4, {sun_family=AF_UNIX, sun_path="/tmp/.s.PGSQL.5432"}, 20) = -1 EACCES (Permission denied)
298   write(2, "FATAL: StreamServerPort: bind() "..., 165) = 165
298   write(2, "/usr/lib/postgresql/bin/postmast"..., 67) = 67
298   _exit(1)                          = ?

Anybody can help me?

Thanks,
Giuseppe