1) Navigate to website.
2) Enter Login Credential.
3) Click on Login.

public class testRegister {
    public static void main(String[] args) throws InterruptedException {

        int i = 0;
        ArrayList<String> ar = new ArrayList<String>();

        System.setProperty("webdriver.ie.driver","E:/Jigar Old Back up/Selenium/IEDriverServer.exe");
        System.setProperty("webdriver.ie.driver.loglevel", "TRACE");
        System.setProperty("webdriver.ie.driver.logfile", "E:/selenium.log");
        DesiredCapabilities ieCapabilities = DesiredCapabilities.internetExplorer();
        ieCapabilities.setCapability(InternetExplorerDriver.INTRODUCE_FLAKINESS_BY_IGNORING_SECURITY_DOMAINS,true);


        WebDriver driver = new InternetExplorerDriver(ieCapabilities);//
        driver.navigate().to("http://172.16.4.90:20125/BPS/");

        driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
        String loginwindow = driver.getWindowHandle();
        System.out.println(loginwindow);

        driver.findElement(By.xpath("/html/body/form/table[2]/tbody/tr/td[2]/table/tbody/tr[2]/td/table/tbody/tr[1]/td[3]/input")).clear();
        driver.findElement(By.xpath("/html/body/form/table[2]/tbody/tr/td[2]/table/tbody/tr[2]/td/table/tbody/tr[1]/td[3]/input")).sendKeys("WCHMOD_MAKER1");

        driver.findElement(By.xpath("//img[@src='images/indeximages/Login_button.gif']")).click();

        for (String winHandle : driver.getWindowHandles()) {

            ar.add(winHandle);
            System.out.println(winHandle);
        }

        driver.switchTo().window(ar.get(ar.size()-1));


        WebDriverWait wait = new WebDriverWait(driver, 10);
        WebElement element1 = wait.until(ExpectedConditions
                .visibilityOfElementLocated(By.xpath("//img[@src='images/wf/Logo2.jpg']")));

        driver.findElement(By.xpath("//div[@class=M5]")).click();

Set <String> handles =driver.getWindowHandles();
Iterator<String> it = handles.iterator();

String parent = it.next();
String child = it.next();

driver.switchTo().window(child);

//perform actions on child window
//perform actions on child window

driver.close(); // only for child wondow


driver.switchTo().window(parent);

//perform actions on parent window
//perform actions on parent window

driver.quit(); // After execution of main thread and for parent window