Firstly, you need to be aware that if you upgrade your graphics driver, you won't be able to run steam, in case you're wanting to upgrade it for gaming purposes. If this is the case, just check that you have the latest supported drivers in settings.
If however you are installing updated graphics driver for other reasons, here is a nice in depth tutorial on upgrading your graphics driver to the latest version. You should also be aware that once you've installed the latest version, there is no easy way back to the supported versions, so make sure you need it before doing it.