echo help needed

[mushu_tea 0]

$q3 = "select * from orders";
$r3 = mysql_query($q3);
$row3 = mysql_fetch_array($r3);
$row3['id'] = $id;
$id = $id ++;

echo "<form action=\"https://www.paypal.com/cgi-bin/webscr\" method=\"POST\">";
echo "<input type=\"hidden\" name=\"cmd\" value=\"_xclick\">";
echo "<input type=\"hidden\" name=\"business\" value=\"phantom_eric@hotmail.com\">";
echo "<input type=\"hidden\" name=\"item_name\" value=\"order $id\">";
echo "<input type=\"hidden\" name=\"amount\" value=\"$total\">";
echo "<input type=\"image\" name=\"submit\" src=\"http://images.paypal.com/images/x-click-but03.gif\" alt=\"Pay with PayPal\">";
echo "</form>";

This is my paypal script..however i cant display the order $id in the paypal site...
anyone can teach me what should i do..in order to display the $id


Next is inserting of multiple $pid that i have...

$q2 = "select pro_id from gallery where pro_id IN (";
foreach ($_SESSION['cart'] as $key3 => $value) {
$q2 .= $pid . ',';
}
$q2 = substr($q2 ,0,-1) . ')';
$pid = $key3;

$insert = "INSERT INTO orders (id,username, pids, total, order_date) VALUES ( '$id','$username','$pid','$total','$date')";
$insert2 = mysql_query($insert);

with this statement..i could only insert a $pid into my database only..how to insert multiple $pid into the db?