For clicking an element you need to find the element adress in which you want to click. :
there are several methods for finding an element for more details you can go here :
http://docs.seleniumhq.org/docs/03_webdriver.jsp#introducing-webdriver
WebDriver driver = FirefoxDriver(); driver.findelement(By.id("ID_of Element")).click();
WebDriver driver = FirefoxDriver();
driver.findelement(By.id("ID_of Element")).click();