How I make acces to my IPB only for Registered users?

There's a group setting to disallow the group to access the site, enabling it will return the login/registration form for guests.

Or by changing the permissions of your apps in the Applications section of the ACP.  There is granular control based on apps, modules, categories, elements …

I've done this in the past. Works very well. The granular permission control of all the IPS constituents is excellent.