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();
    
    }

}