Unable to connect To Database...

hi...
I am doin my project in PHP with PostgreSQL as backend...
Both r very new to me....
My OS is LINUX
I am trying to connect to the database bt its not getin connected...
By using
"su posgres" command
i hav created user "root" and database "sample"
By using
"psql -U root sample" command
i hav created table "login" and inserted 3 data's...
now through code using PHP i am trying to insert the data but connection is not getin established..
the code to connect to the datadase is :-

<?php
require_once "DB.php";
$uname=$_POST['uname'];
$pass=$_POST['pass'];

$username="root";
$password="";
$hostname="localhost";
$dbname="sample";

$db=new DB;
$dsource=$db->factory("pgsql");

$dcon=pg_connect("dbname=sample user=manashi");

$sql="insert into login values('$uname','$pass')";

$rs=$dsource->pg_query($sql);
?>

is there anythin wrong with the code or sum other problem
waiting for the reply...