Are you in the right place...
Do you have the downloaded Nvidia file in your "/home/xxxcomputer" directory or have you changed to the directory to which you have downloaded the file?
"init3" usually defaults to the "/home/xxxcomputer" directory, but if you have problems with juggling permissions, copy the downloaded file to the root directory and work from there.
As it stands, it sounds as if you have changed(cd) into your root directory, where there is no downloaded file, instead of becoming root, and then placing yourself(cd) in the directory where the file is located. There is a difference between having root privileges and being in the root directory.
See the Nvidia README and the section on Installing the NVIDIA Driver-Starting the Installer.