Hi Rachid,
I would recommend to not implement password storage/comparison on your own and rely on Mendix security expertise for that part of the application. IOP you should use the login.html page that comes by default in your mendix project, you can style it to your liking.
If you need more customization and really want to have a mendix page to serve as a login page then take a look at https://appstore.home.mendix.com/link/app/87/Mendix/Login-form
-Andrej