libpq connectivity

Hello,

I am working on Linux RH 6.0 platform.
I want use PostgreSQL as a backend. 'C' language as a front-end.
I am not able to connect to each other.
I am using libpq.
The program is :-

/*conn2.c*/
#include <stdio.h>
#include "/usr/include/pgsql/libpq-fe.h"
 main()
 {
     char       *pghost, *pgport, *pgoptions,*pgtty;
     char       *dbName;
     PGconn     *conn;
     pghost = NULL;              /* host name of the backend server */
     pgport = NULL;              /* port of the backend server */
     pgoptions = NULL;           /* special options to start up the backend
                                  * server */
     pgtty = NULL;               /* debugging tty for the backend server */
     dbName = "template1";

     /* make a connection to the database */
     conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);
}

The compiling is ok, but linking have error.
$ gcc conn2.c -c -o conn2
No error

The program compile and linking result :-
*****************
$ gcc conn2.c -o conn2
/tmp/cchKU26L.o: In function `main':
/tmp/cchKU26L.o(.text+0x47): undefined reference to `PQsetdbLogin'
collect2: ld returned 1 exit status
*****************

How to remove this linking error, or how to make link between PostgreSQL and
'C'?
Thanks in advance
Anuj