p2p ip connection problems

I can connect to the database on the server machine using pgadminIII
and, it installed as a windows service. And I created one test database called usfo

I have not succeeded in getting it to work yet using pg explorer from another client machine on the p2p.

I followed Tony's suggestions
namely
In pg_hba.conf
I added
host all all 192.0.0.101/32 md5

(my client machine is 192.0.0.101)
and I changed postgresql.conf to say
listen_addresses = '*'
========================
PG Explorer on my client is asking for:
COMMON NAME: ??? (I am uncertain about this)
HOST: 192.0.0.9
Default database: ??? (I am uncertain about this)
Database port: 5432

======================================
I know absolutely ZERO about any of this stuff.
All I know is to go to the DOS prompt and key in
IPCONFIG and it tells me, on the machine I want to
use as client, IP Address 192.0.0.101, subnet mask
255.255.255.0 default gateway 192.0.0.254

and on the machine which has postgresql for
windows, if I do ipconfig, it says...

IP address 192.0.0.9
subnet mask 255.255.255.0
default gateway 192.0.0.254
Our company has ZERO money to give to consultants,
so please dont suggest that. If I cant figure out
how to make this work, then we just live without
it. But it would give me a tremendous sense of
personal satisfaction to prove to myself that
postgresql can work on this little p2p network, and
I could do one or two useful things to help the
office.

There MUST be some little command I can run to tell
me the secret numbers and how to plug them into the
config files for postgresql. It can be rocket
science.

I can tell you that we have a Xyzel router to bring
in the DSL, and a Cisco Linksys hub... if that gives
any clues.