出现这个报错怎么办

Exception in thread "main" org.openqa.selenium.WebDriverException: Cannot find firefox binary in PATH. Make sure firefox is installed. OS appears to be: VISTA

Build info: version: '2.46.0', revision: '87c69e2', time: '2015-06-04 16:17:10'

System info: host: 'Alcour', ip: '10.4.104.16', os.name: 'Windows Vista', os.arch: 'amd64', os.version: '6.2', java.version: '1.6.0_13'

Driver info: driver.version: testDriver