using POSTGRES in a network

we're now developping a system on Linux, using PostgreSQL.
and the question this time is about
how to connect to the DBserver through the network (ex,ethernet) from
clients.
especially on CODINGS.

we found a lot of info about the way of connecting
between DBserver on Linux and Windouws user.
but few about the Linux-Linux DBconnection, which we do need.
is anybody knows about this? or have anyone tried it before?

when you connect to the remote DBserver from Windows,
what you need is to set the IP of the server in "hosts"file
and to set your IP as DBuser to the server machine.
and you can access through the command-line, using "psql"
but if you wannna do this on the programs??????
can you do the same thing using the function such as "db_connect" or
PGDBfunctions???
we also need the info about this.

we do appreciate for your reply . thanks.

hiroko