using pgsql on my comp only without tcp

hi, i am unable to setup my modem on my redhat 8.0 OS, so i don't think i can 
get TCP access.  is it possible to use pgsql entirely on my local computer 
(i.e creating my own databases & manipulating them on my comp)?. what 
variables do i need to alter to do so?  i just want to be able to simulate the 
labs for my 300 level uni course so i practice using databases.  i am also 
having difficulty finding my postgresql.conf file.  i have my psql & 
postmaster files in the following directories:

/usr/bin/psql
/usr/bin/postmaster

but i can't find any pgsql folder grouping pgsql stuff together.

thanx, sam