The Nvidia website has everything you need to get up and going.
The second link down gives you a link to what you need to read first, before you download the driver.
Nvidia Installer HOWTO for SUSE LINUX users
Download the driver that pertains to your card
Unix Drivers Portal Page
This is a page for the Nvidia card I have in my very old box. (This is an example, you have to get the driver pertaining to your card)
Linux Display Driver - x86
It gives you step by step instructions on how to install the driver.
To drop down to init 3, you use ctrl+alt+f1
This will bring you to tty1. Login as root and type
init 3
Then install the driver
To get back to the GUI type
init 5
Hope this helps!