How to pass arguments from computer via USB

What I want to do is send a message to the monitor from Arduino asking for input (I know how to do this), and be able to respond via "Send" button in monitor.

It's the response that I don't know how to do.

I'm sure it's simple but can't find any examples anywhere.

You need to look at the "Serial" "read" and "available" methods. http://arduino.cc/en/Tutorial/SerialCallResponseASCII

Perfect Thanks. -Jake