Hi Bikram,
You can enable anonymous users in the Project security dialog box. I would create a new user role for anonymous users and set the anonymouse user role, to the new user role.
Using a go home microflow or a role based home page in the navigation menu, you can build a page to your specifications. To log a user in, you can use this widget
https://appstore.home.mendix.com/link/app/87/Mendix/Login-form