You go to the manufacturer's site, to the support section, and look up that model: http://support.lenovo.com/en_US/detail.page?LegacyDocID=MIGR-46024
Please satisfy my curiosity and help me provide better help to future posters: How do you know that a driver will resolve your issue? Did you just re-install the OS? Is there an indication of a driver problem in Device Manager? Thanks.