Let's start with Arduino that will receive the RF signal. You'll need to plug it into the host computer via a USB cable in order to upload a program. In order to debug both of these devices, you will also need two computers, one to run an Arduino IDE for both the transmit and receive device. You can also do this with a single computer and two USB ports (for more information on how to do this, visit http://forum.arduino.cc/index.php?topic=407.0). However, once you've created the program, you can disconnect the remote Arduino from the computer and power it from a battery. In this example, you'll use the example programs from the library to send data from the client (Arduino connected to the PC) to the server (the standalone Arduino) and then have it echo back.

As you did earlier, you'll first need to install the library. There are a couple of possible libraries, but the one that is the most full featured is the RF24 library, which is available...