如何为sql server express数据库启用成员资格提供程序

I am playing with ASP.NET MVC with visual webdeveloper express edtion 2008 and sql server express edition. I am creating a site that will use membership provider for that i want to use my own databse not the application services database. I have created my database in app_data folder but still I am not able to register it using aspnet_regsql command. It is not showing that in list.Can any one suggest the way for enabling my database for membership providerI am playing with ASP.NET MVC with visual webde