You have to download a small script from the nvidia website (choose your system architecture first) www.nvidia.com/object/linux.html,
which does the istalation procedure of the drivers ...
It is so somplicated by the nvidia comp. because the drivers are not licensed open source.
There is a how to to read before the actual install process. You'll find it in the download package.
If you find the how to confusing, get back and post your question.