Have you changed your working directory to the directory to which you downloaded the driver? The driver can not be found by the shell, so it is very likely that the path you gave is not the right one. For example, when you downloaded the driver to the
Download directory in your home the the correct path would be
Code:
~/Download/ati-driver-installer-11-9-x86.x86_64.run
Also keep in mind that the name of the installer and the version number changed, since that how to was written, double-check that.