How do I open a use asp.net to send/receive post/get requests

I'm trying to build a c# web page that accepts xml code generated by another computer. So I want to accept a string and then send it into my code. I have looked here: Getting a POST variable but that question lacks the explanation of how to invoke your code opon receiving a request. Reading: http://ift.tt/1KgiYII as suggested in How to send and receive the POST request in asp.net? didn't help either.

something like what I want is:

public partial class WebForm1 : System.Web.UI.Page{
            BaseSocket bs = new BaseSocket();
    public void OnReceivedPost(object sender , string value)
        {
            bs.ConnectToCode(value);
        } 
 }

So that if the other send a web request to www.example.com then it goes into my code (connectToCode).