While there are going to be some differences between the type of cable and LAN testers on the market, you will find that they all have a relatively similar method of working. You will take one end of the cable and hook it up to the transmitter of the device, and you will hook up the other end of the cable to the receiver on the tester. Make sure that the cables are fully plugged in first. You will then send a signal through the tester. It will go from one end of the cable to the other end. You can then read the report on the tester to see if there were any problems or faults with the cable. This will let you know whether the cable is good or if it has problems.