PHP – How to Update Cart Quantity

I use this code to create and add an item into the cart.

Here it is:

<?php
    error_reporting(E_ALL | E_STRICT);
    $mageFilename = 'app/Mage.php';
    require_once $mageFilename;
    $app = Mage::app('default'); 
    Mage::app();

Mage::getSingleton('core/session', array('name' => 'frontend'));

    ini_set('display_errors', 1);

$TITLE = $_POST["TITLE"];
$SKU = $_POST["SKU"];
$MANUFACTURER = $_POST["MANUFACTURER"];
$RNUMBER = substr(number_format(time() * rand(),0,'',''),0,4);
$SKUNUMBER = "$SKU-$RNUMBER";
$DESCRIPTION = $_POST["DESCRIPTION"];
$SHORTDESCRIPTION = $_POST["SHORTDESCRIPTION"];
$IMAGE = $_POST["IMAGE"];
$PRICE = $_POST["PRICE"];
$COUNT = $_POST["COUNT"];
$PRODUCTLINK = $_POST["PRODUCTLINK"];
$PRODUCTCOLOR = $_POST["PRODUCTCOLOR"];
$SizeOfProduct = $_POST["SizeOfProduct"];
if($SizeOfProduct == ""){
$SizeProduct = $_POST["SizeOfProductSD"];
}
else {
$SizeProduct = $_POST["SizeOfProduct"];
}

if($SizeProduct == ""){
$SizeProduct = "Само един е размера";
}

$ADDEDPRICE = $_POST["ADDEDPRICE"];

    $api = new Mage_Catalog_Model_Product_Api();

    $attribute_api = new Mage_Catalog_Model_Product_Attribute_Set_Api();
    $attribute_sets = $attribute_api->items();

    $productData = array(); 
    $productData['website_ids'] = array(1); 
    $productData['categories'] = array(2,3);

    $productData['status'] = 1;

    $productData['name'] = utf8_encode($TITLE);
    $productData['description'] = $DESCRIPTION;
    $productData['short_description'] = "$SHORTDESCRIPTION<br>Посочен размер: <b>$SizeProduct</b></b>";
    $productData['ext_image'] = $IMAGE;
    $productData['product_link'] = $PRODUCTLINK;
    $productData['product_color'] = $PRODUCTCOLOR;
    $productData['product_size'] = $SizeProduct;
    $productData['product_add_price'] = $ADDEDPRICE;
    $productData['url_key'] = $SKU;

    $productData['price'] = $PRICE;
    $productData['weight'] = 0.50;
    $productData['tax_class_id'] =2;
    $productData['page_layout'] ='one_column';

    $new_product_id = $api->create('simple',$attribute_sets[0]['set_id'],$SKUNUMBER,$productData);


    $stockItem = Mage::getModel('cataloginventory/stock_item');
    $stockItem->loadByProduct( $new_product_id );

    $stockItem->setData('use_config_manage_stock', 1);
    $stockItem->setData('qty', 10);
    $stockItem->setData('min_qty', 3);
    $stockItem->setData('use_config_min_qty', 1);
    $stockItem->setData('min_sale_qty', 3);
    $stockItem->setData('use_config_max_sale_qty', 1);
    $stockItem->setData('max_sale_qty', 0);
    $stockItem->setData('use_config_max_sale_qty', 1);
    $stockItem->setData('is_qty_decimal', 0);
    $stockItem->setData('backorders', 0);
    $stockItem->setData('notify_stock_qty', 0);
    $stockItem->setData('is_in_stock', 1);
    $stockItem->setData('tax_class_id', 0);

    $stockItem->save();



$_product = Mage::getModel('catalog/product')->load($new_product_id);

$adress = (string)Mage::helper('checkout/cart')->getAddUrl($_product);

$hm1 = array('SignProduct.php/');
$ym1   = array('');
$adress = str_replace($hm1, $ym1, $adress);

header('Location: '.$adress.'');


?>

Take a look:

All items that i include in the cart by this script has selected quantity of 1.

How can i add an item into the cart with selected quantity of 3 for example ?

Thanks in advance!