I would recommend starting an app with a framework that takes care of all that for you. eg. The Mere Mortals Framework! (Kevin McNeish, please direct deposit my commission check)

>This is somewhat of an open ended question, but what's the right way to do application security and user authentication?
>There seems to be more than a few ways to do this, such as http://stackoverflow.com/questions/326818/c-how-to-validate-domain-credentials and http://msdn.microsoft.com/en-us/library/ms733131.aspx.