First of all, buy an ethernet crimping tool from the above list. Even you can buy a cat5 cable from Amazon. Now using your crimper blade trim wire insulator. Now you will find 4 pairs of twisted cable. Now arranged them in this order – green and white-green, orange and white-blue, blue and white-orange, brown and white-brown. line up the 8 wires neatly and put it into the plastic head of RJ45 connectors. After that, you can check that connectivity on the cable tester.