There is several ways to add order history, with less or more data
Quick way :
$message = 'Comment to add in order history'; $order->addStatusHistoryComment($message); $order->save();
With all informations :
$history = Mage::getModel('sales/order_status_history') ->setStatus($order->getStatus()) ->setComment('Comment to add in order history') ->setEntityName(Mage_Sales_Model_Order::HISTORY_ENTITY_NAME) ->setIsCustomerNotified(false) ->setCreatedAt(date('Y-m-d H:i:s', time())); $order->addStatusHistory($history); $order->save();