Hi Lily, to type text into a textfield using Ruby Selenium Webdriver, you can use send_keys method. This method basically takes your keyboard input and writes it into the identified textfield. Following example shows how to do that:
driver = Selenium::WebDriver.for :firefox
driver.navigate.to "https://www.facebook.com"
el = driver.find_element(:id, "email")
el.clear
el.send_keys "abha.rathour@edureka.co" #send_keys method takes the keyboard inputs