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