My my, you haven't reached yet the point where you ask yourself "which is my root password"?
Ok, tell what distro are you running and, if you know, what desktop manager.
Anyway, when you installed your distro (if is you the one who got it installed), it should have asked you about an account name and two passwords. One for the account name you provided, a regular user one, and one for the super user a.k.a. "root".
You should memorise that root password the same way you memorise your birth date. Because the root account can do practically everything on your computer, while a regular user can't.
That password am I talking about. Try and remember it.
Then start reading some tutorials about Linux. You'll find some here at LQ, or take the begginer's course at www.linux.org
or wherever you want.