Authorize .Net Payment Gateway

Question

In one of my shopping cart application, i have to use Authorize.Net Payment Gateway (Server Integration Method (SIM)).Once customer select the Products and click to Proceed, he has to redirect to payment Gateway  to enter the Card Details etc. After enter the details from Payment Gateway, the Customer could view the response Message (Transaction Message) in Merchant Site. How to show the Transaction Details from Payment Gateway to Merchant Site.