ASP.NET login control works with the ASP.NET membership and Roles mechanism. You can use the default mechanism or customize the membership providers. details below:
Understanding ASP.NET Roles and Membership - A Beginner's Tutorial
Although sometimes we may not want to have the memebrship database and use our own database instead. in that case this login control cannot be used as is. we will need to write our own code to handle the authetication and authorization in this case. details below:
Understanding and Implementing ASP.NET Custom Forms Authentication
I hope this reference will help you in your problem. if not do let me know and I will try to refine my answer.