Visual Web Developer 2008 - Locking Down Application

I am using the new Visual Web Developer 2008 Express Edition and SQL Server 2005. I have no problem connecting to the database to show dynamic data using the GridView, FormView, etc, but I can't seem to use the Login tool to create a way to lock down the application. I get a message saying "Error invoking 'Administrator Website' Details: Exception has been thrown by the target of an invocation."

1. Are all usersconfigured using the Microsoft SQL Server Management Studio? Can I add more than 3 users? If so, how do I connect the two apps?

2. Is there an easier way to lock down the app using a login box?

Thanks for the help. Let me know if you need additional info.