How do I build a web service for non-local host?

I know this is a newb question, but I don't get it! I want to build a simple web service that I can deploy/install on my choice of web host. I started up VS2008, and selected File - New - Web Site. I select the ASP.NET Web Service template, and am using Visual C# for language. What do put for Location? HTTP seems to be the only choice in the dropdown that makes sense. At build time, I don't know what server(s) this is going to be running on, so what do I put for the URL? If I don't put anything in the box, the 'OK' button is disabled, and I can't continue.

If you can give me some background, along with your answer, I would really appreciate it. What is VS doing with these values?

Thanks.

When you create the new project, enter a local url (or file path).

After you build the service, you can deploy it to a different host.