Hey Jeevika, you can use following automation script to select a date from a datepicker div in Webdriver:
driver = new FirefoxDriver();
driver.get("http://jqueryui.com/datepicker/");
  driver.switchTo().frame(0);
  driver.manage().timeouts().implicitlyWait(60, TimeUnit.SECONDS);
  driver.findElement(By.id("datepicker")).click();
  driver.manage().timeouts().implicitlyWait(60, TimeUnit.SECONDS);
  WebElement dateWidget = driver.findElement(By.id("ui-datepicker-div"));
  List rows=dateWidget.findElements(By.tagName("tr"));
  List columns=dateWidget.findElements(By.tagName("td"));
  for (WebElement cell: columns){
   //Select 10th Date
   if (cell.getText().equals("10")){
   cell.findElement(By.linkText("10")).click();
   break;
   }
  }