I suspect your problem is that filenames and directories are case sensitive in Linux/unix and the dir you want to see is /usr. You do not have to be root see /usr, but you might have to be root to some change things.

If you are using Ubuntu, become root this way:

sudo cmd

where cmd is the command you want to run. sudo will prompt for a password, which is your user password on Ubuntu.

If you are not using Ubuntu, then go into superuser (=root) mode:

su

and it will prompt for the root password that you set up when you installed the distro.