i just have a birds eye view of a article from this url
http://www.codeproject.com/Articles/578374/AplusBeginner-splusTutorialplusonplusCustomplusF
so few questions comes to my mind and those are as follows
1) first of all tell me what are you trying to say custom form authentication ?
form authentication means user send their login details and routine will check that user's credentials is valid against db. if found valid then auth ticket will be forwarded to user pc but why the word custom form authentication has been used?
2) this is the function public ActionResult Login(User model, string returnUrl) will call when user submit their login details. so i like to know when this function Application_PostAuthenticateRequest() will call ?
3) does this function Application_PostAuthenticateRequest() will call after successfully login ? Go to the complete details ...