Magento How to add new products

require_once 'app/Mage.php';
Mage::app();
 
// instatiate Product
$product = Mage::getModel('catalog/product');
 
$product->setWebsiteIds(array(1));
$product->setSku('rand-sku-' . rand());
$product->setPrice(rand(100,2000));
$product->setAttributeSetId(4); 
$product->setCategoryIds(array(3));
$product->setType('Simple Product');
$product->setName('Product Name'.rand(1,200000));
$product->setDescription('The Product Description');
$product->setShortDescription('Brief Description');
$product->setStatus(1); 
$product->setTaxClassId('2');
$product->setWeight(0);    
$product->setCreatedAt(strtotime('now'));
 
/* ADDITIONAL OPTIONS 
 
   $product->setCost();
   $product->setInDepth();
   $product->setKeywords();
 
*/
 
$product->save();
 
// "Stock Item" still required regardless of whether inventory
// control is used, or stock item error given at checkout!
 
$stockItem = Mage::getModel('cataloginventory/stock_item');
$stockItem->loadByProduct($product->getId());
$stockItem->setData('is_in_stock', 1);
$stockItem->save();
 
header("Location: /checkout/cart/add/product/".$product->getId()."/);