hi rong...
well...is the postmaster running ?
there are a couple of postintallation steps ...
first, you must create and prepare the data files.
lets assume your pgSQL is installed on /usr/local/pgsql, right ?
1 . make dir where your data files are going to live, say data
root# mkdir /usr/local/pgsql/data
2 . lets make user postgres the owner of this dir
root# chown postgres /usr/local/pgsql/data
3 . let postgres init dababase on this dir
root# su postgres
postgres# /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
4 . start the postmaster..
set the environment var PGDATA=/usr/local/pgsql/data
postgres# /usr/local/pgsql/bin/postmaster -i
-i allows tcp connections to the db.
5 .start the client
postgres# /usr/local/pgsql/bin/psql
There is are various front end GUI's to postgres..one I use is pgAccess-- go to their page and lurk a bit ..
If you don't have the postgresql docs, you should take it on the postgresql.org site because there are a lot of options to postgresql be compiled with depending on further use you are going to do..to conect via Java, C++... and any way...printing this docs you'll find most of your answers faster. There are the admin, programmer, user...guides..and a small tutorial..
Good luck .. and best regards,
Andrew