you have to be a little more clear... do you want to be able to retrieve and update the database(s)? what languages and environments are you going to use? (ASP.NET/C#?) with ASP.NET and visual studio, i would start with making a simple web service application, then write the methods i would want to expose, along with any private methods required if you intend to send and receive any complex data, then you should probably design your message format beforehand. see Place XML Message Design Ahead of Schema Planning to Improve Web Service Interoperability also a general guide to webservices: How ASP.NET Web Services Work