root is the master account in Ubuntu; every account has limited privileges but the
root account has no limitations. The reason for hiding
root is that in most cases you don't need root access. The analog in Windows would be having to authenticate when you want to install a driver; in Ubuntu you have to be root or have root privileges.
There are two ways for you to get access as root. You can type:
sudo <whatever-command> and Ubuntu will ask you for your password and then execute that command as root.
sudo su, where you'll input your own password and then you will become root (i.e. you will be logged in as root).
I prefer the latter because it gives me more control; sometimes running a command just as root isn't enough, but doing it this way can be more dangerous (i.e. you could accidentally cause more damage).
I recommend trying the first way. And then trying the second way if that doesn't work. Just make sure you get out of root after you're done (i.e. type
exit after you're finished doing what you need to do as root).