Well, there's not really such thing as an "ASP.NET desktop application". To call it a "desktop application" implies that it is running locally, while ASP.NET applications inherently run on a remote server and are displayed in a browser. Which is it that you want? I can't see anyone running a POS application over the web.
Also, what do you mean by "data". I would now assume you mean a database but from your first post it could have meant anything. If you mean a database then please say that. In future, please don't be so economical with your words. Assume that two brief sentences will never be enough to adequately describe your issue to those who have no prior knowledge of what you're doing. If you'd like us to take the time and make the effort to help you then please do us the courtesy of taking the time and making the effort to post a FULL and CLEAR description of your issue.
If you do mean that you want to connect to a database remotely then you can do it directly by simply specifying the server address in your ADO.NET connection string. It may be a better idea to use a web service though.