Hi,
but now I have this error: "Error: 403 Access Forbidden". Why?
I don't know, this not seems application error, this seems webserver restriction. To check this we need site details (also FTP) and a guide step by step to reproduce this error on your site.
Has Easy Profile a module to add a user on FrontEnd?
No sorry, Easy Profile extends Joomla user management (not replace), so registration and edit profile pages are the same of Joomla (with many improvements). This is the most important feature but it give some restrictions because Joomla not allow this.