There are a couple of ways of doing this in .Net.

The first is .Net web services, that run as a .asmx file. See http://quickstarts.asp.net/QuickStartv20/webservices/default.aspx

The other is using the new Windows Communication Foundation.

>I need to learn about Web Services. I know nothing at all about it, and I need to
>look at a C# app using WS.
>
>Can someone point me in the right direction?
>
>Thanks