Now take the snap-on ECG electrodes and stick one to the prepared site on your left lower rib area (site 1), and one to the prepared site just below your right collarbone (site 2).

Insert the plugs of these electrodes in the blue-ringed ECG sockets on the underside of the headbox as shown in the image (don't worry about which goes in the left or right ECG sockets – they are interchangeable).