Mandriva administrator login

Can someone please tell me how to login in to get administrator privlages.
I have a 300 gig Hdd (external) that I plug into the USB port but I can't access the Hdd because it says I don't have adminstrator privledges, how do I get those privledges to read the Hdd. It won't let me login in as root when I start the system. Also I need admin for installing programs.

Thank you,
Kwdaye

If you have a user login to use, login as that user and run: su root
It will ask for the root passwd.
Enter it and do whatever you want.

you'd actually just need to enter su
no need for the word root after it
you can also enter su - (notice the minus sign)
if you'd like to be in the terminal as though
you were logged into the computer
as the root user