driver.findElement(By.cssSelector("Tag#Value of id attribute"))

driver.findElement(By.cssSelector("input#fname"))

driver.findElement(By.cssSelector("button#idOfButton")) 

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.remote.DesiredCapabilities;

public class SampleOne {

	public static void main(String[] args) {
		
	 // System Property for Gecko Driver 
	System.setProperty("webdriver.gecko.driver","D:\\GeckoDriver\\geckodriver.exe" );
		
       // Initialize Gecko Driver using Desired Capabilities Class
		DesiredCapabilities capabilities = DesiredCapabilities.firefox();
		capabilities.setCapability("marionette",true);
		WebDriver driver= new FirefoxDriver(capabilities);
		
	
      // Launch Website
driver.navigate().to("https://www.testandquiz.com/selenium/testing.html");
	
      // Click on the textbox and send value
driver.findElement(By.cssSelector("input#fname")).sendKeys("JavaTpoint");
	 
	// Click on the Submit button using click() command
driver.findElement(By.cssSelector("button#idOfButton")).click();
 
		
	 //  Close the Browser
	         driver.close();
	
	}

}