I compiled the PostgreSQL using the commands rpm -ivh *.rpm and installed it but as I want to install DSpace I have to follow the steps as follows
Once installed, you need to enable TCP/IP connections (DSpace uses JDBC). Edit postgresql.conf (usually in /usr/local/pgsql/data or /var/lib/pgsql/data), and add this line:
tcpip_socket = true
Then tighten up security a bit by editing pg_hba.conf and adding this line:
host dspace dspace 127.0.0.1 255.255.255.255 md5
Then restart PostgreSQL.
But I could not find the file postgresql.conf in either of the directory as suggested.
So I tried to erase the PostgreSQL using rpm -e *.rpm and it gave an error message that Postgre ... packages not installed
so I tried rpm -i *.rpm and its message was more shocking saying that its already installed.

