To update our store orders on some other website other than our magento store we need to send the orders details after successful order at our store.To do this we need to dispatch a method after success action. So we need to create a module in our ocal folder of magento . Here our module name is Postdata with package name Letsknnowit OR we can write this code in any other module also. We need to write some code in config.xml and Observer.php

File: app/code/local/Letsknowit/Checkout/etc/config.xml

<config>
    <global>
       <models>
         <letsknowit_checkout>
 <class>Letsknowit_Checkout_Model</class>          
    </letsknowit_checkout>
       </models>
    <events>
      <checkout_onepage_controller_success_action>
       <observers>
         <postDataTosServer>
            <type>singleton</type>
              <class>Letsknowit_Checkout_Model_Observer</class>
              <method>postDataTosServer</method>
        </postDataTosServer>
      </observers>
     </checkout_onepage_controller_success_action>
  </events>     </global>   </config>

After successfull order in magento the observer is dispatched . In observer.php we will get the order details and send it to the url of other server via CURL method.

File: app/code/local/Letsknowit/Checkout/Model/Observer.php

<?php 
class Letsknowit_Postdata_Model_Checkout_Observer 
{
     public function postDataTosServer(Varien_Event_Observer $observer){
       $orderIds = $observer->getData('order_ids');
         foreach($orderIds as $_orderId){
            $order     = Mage::getModel('sales/order')->load($_orderId);
           $customer  = Mage::getModel('customer/customer')->load($order->getData('customer_id'));
           $customer->getDefaultBillingAddress()->getLastname();
           $billingaddress = $order->getBillingAddress();

          try {  /* parameters can be change according to requirment */
                $params =    array( 'customerName'=>$order->getData('customer_firstname'),
                            'companyName'=>$billingaddress->getData('company'),
                            'telephone'=>  $billingaddress->getData('telephone'),
                            'email'=> $billingaddress->getData('email'),
                            'street'=> $billingaddress->getData('street'),
                            'city'=>  $billingaddress->getData('city'),
                            'region'=> $billingaddress->getData('region'),
                            'postcode'=> $billingaddress->getData('postcode'),
                            'total'=>$order->getGrandTotal() );

            $url= 'exmaple.com/getorders.php';         // the url on which the data will be send through curl
            $ch = curl_init();
            curl_setopt($ch, CURLOPT_URL, $url);
            curl_setopt($ch,CURLOPT_HEADER);
            curl_setopt($ch, CURLOPT_POSTFIELDS, $params);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
            curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);
            $response = curl_exec($ch);
            curl_close($ch);
        Mage::log('Order has been sent to exmaple.com');
 
         } catch (Exception $e) {
               Mage::logException($e);}
      }
         return $this;
     }
 }   ?>