I've heard that the higher account on freeBSD was "*". But, how to log in as it? I've never set a password for it.
So, I want to know its account name and where is the password.I think the username is EITHER "ROOT" or "*" and the password either "root" or nothing (just hit enter)it's root, just as with all UNIX based systems.

When FreeBSD is first installed, you are offered the option, during installation, to specify a root password.    If that was done, then that is it.   If not, there is no root password.   You could log in to root without a password - a dangerous situation which should not be LEFT that way.

But, the system is also set up by default to disallow a root log-in from a remote host.   So, you would have to be at the console in order to log in as root unless that has been modified.

If you are at the console, you will need to do a boot to single user mode, do an fsck and then mount needed file systems.  Then you can set the root password and any config stuff to allow logins as needed.
But with root, I can't edit the /usr/ directory.BC_Programmer was RIGHT with the suggestion given.

After booting into single user and creating the root password, you exit then log in as root.
It isn't a wise choice to edit an entire directory as a beginner. Learn the system first.