Handle Multiple Resposnses for a single request

Question

I have created a Window application to upload the file on server using Http Post method and Recieving the response. I am not much aware of the application which runs on the server side to receive requet and Send Resposne So i created  a Normal .net Application with HttpListener in it which will listen to request and send Resposne for it.
Intially every thing was fine but Now we got a requirment in which We can have Multiple Response for a single request . and All these resposnes will not come together they might come at anytime. Please let me know that how should I handle this scenario in my Window  application which is working like Client(Sending request)