http://ubuntuguide.org/wiki/Ubuntu:H...ricted_drivers
the nvidia driver is in the restricted modules section of Ubuntu.
alternately you CAN use the one from nVidia if you so desire..
I would copy that nvidia file to someplace on the hard drive that is easy to get to .. say your home directory rather than the Desktop.
CTRL+ALT+F2 to switch to a terminal
sudo su
/etc/init.d/gdm stop to shut down X
cp /etc/X11/xorg.conf /etc/X11/xorg.conf.bak
cd /home/<username>
chmod +x NVIDIA-Linux-x86-100.14.11-pkg1.run
./NVIDIA-Linux-x86-100.14.11-pkg1.run
Follow the prompts as the installer runs, the defaults are usually acceptable. it will compile a kernel module for your machine and install it. It will then give you the option to use an nvidia utility to configure your xorg file, I suggest you use it.
/etc/init.d/gdm start to restart X
Installing the driver from the restricted modules section of Ubuntu will surely be easier.