Have you tried rebooting your computer yet? I wuld definitely recommend that before anything else.

To update your graphics driver your first need to find out what graphics adapter or card you have.
To find that out, click Start > Control Panel > System > Hardware > Device Manager > Display Adapters, and note down what appears after the last step.

Then you need to find the appropriate graphics driver from the internet. Post the display adapter that you find above, and we can check the driver from there.