If everything went ok after the reboot, you should be prompted by windows that new hardware is found and will ask you for the drivers. In the box that your video card came in you should've received a CD or Disk with the drivers on them, if not you'll have to let windows install the Standard Graphics Adapter drivers.
Some video cards have different driver installation processes.
There are a few different ways you can install the drivers so for the best way for your video card look in your card's manual. If you got no CD or Disk with your video card go to your card's manufacturer site and download the latest drivers. Now I will go through some problems your might have after installation. Try putting the old card back in and see if that works. To fix this go to the website of the manufacturer of your monitor and download the correct driver for the model you have.