The NRC Tasker is the tool that lets NRC know a machine is ready to render. By default, when you install as a render node, it is started at login when you boot the machine. It is recognized by a green LightWave icon in the Windows taskbar or the Macintosh Dock. In a normal install, you are asked at the end of the install procedure if you'd like to start the NRC Tasker.
Once you have started the Tasker, you can right click on the green LightWave icon and set the NRC Tasker to start at Login.