Processing app that used serial method to talk to arduino need the correct port to connect with.
This app can help you:
processingScanner (run on 64bit computer)
![scanner](http://tech.yeesiang.com/wp-content/uploads/2015/04/scanner.png)
Double check with your control panel -> Device Manager.
![deviceManager](http://tech.yeesiang.com/wp-content/uploads/2015/04/deviceManager.png)
Device Manager show COM16 where our arduino board connected with, is match with index 0 in the processingScanner. So, the number/index to use in process is 0.