I need to automate the "Browse" button click from Selenium.

For this, I have tried
driver.findElement(By.xpath("//*[@id=\"dnn_ctr383_View_filename\"]")).click();
and
driver.findElement(By.cssSelector("Css path")).click();
Both gives me org.openqa.selenium.NoSuchElementException: Unable to locate element: exception.
I have seen this link here where the author suggest to use AutoIT, but in step 2, the script, the author has created is for IE. Can someone please suggest, how I can automate the "Browse" button click in firefox?
Any help is much appreciated.