How to tell ubercart after the payment is completed?

Hi,

Thank you very much for this code. I created my own gateway based on your code. It works great. However my question is what is the code to tell ubercart that the payment is already completed, failed or cancelled?

I have already set the code to redirect to my merchant gateway but I don't know how to send back the info to tell ubercart about successful payment.

Without using a module here's the simple code to my merchant payment gateway:

<form name="payFormCcard" method="post" action="https://test.mymerchantgateway.com/payment/pay.jsp">
<input type="hidden" name="merchantId" value="1"> 
<input type="hidden" name="amount" value="3000.0" >
<input type="hidden" name="orderRef" value="000000000014">
<input type="hidden" name="currCode" value="608" >
<input type="hidden" name="successUrl" value="http://www.mydomain.com/Success.html">
<input type="hidden" name="failUrl" value="http://www.mydomain.com/Fail.html">
<input type="hidden" name="cancelUrl" value="http://www.mydomain.com/Cancel.html">
<input type="hidden" name="payType" value="N">
<input type="hidden" name="lang" value="E">
<input type="submit" name="submit">
</form>

under "successUrl" I need to know what is the url of ubercart to accept a successful/complete payment.