If you are working in Silverlight, you could create a new application using the Silverlight Business Application template. The resulting code shows you some of the functionality of adding a new Member.
Also, Visual Studio has a built-in feature that allows you to manage users through a simple web-interface. It is called ASP.NET Web Site Administration tool.
Finally, you can add code to your ASP.NET WebForms, MVC, WinForms, or WPF application. The Membership API is fairly straightforward and I would suggest you start by following the Login, Logout service layer methods to get a feel of the data-flow.
Dan McMillan, Aug 25, 2010