A very simple DIY task, but one that is important you get right. The plug of any electrical device is about as close as you will ever get to the wiring, but it is also the part which gets pulled and pushed and knocked around. Making sure that it is wired correctly and securely is very important, both for your safety and for the safety of the device it is connected to.
Remove the plug cover by unscrewing the single large screw. Hold the flex (cable) over the plug so you can see how much of the sheath you need to trim back. The plastic clamp at the bottom of the plug much clamp onto sheath rather than the conductor wires, so make sure you don’t trim too much. Once you know how much you need to trim, cut the sheath carefully along its length and peel it back. Trim off the correct amount carefully.
Position the flex on top of the plug again and mark how much of the conductor sheath’s you need to trim. You need to aim to have the conductor wires take the most direct route to the terminals and to lie in the channel out of harms way. Trim the conductor wires to size if needed, and then strip about 10mm of insulation from the end of each wire. Wire strippers will make this easier, otherwise you will need to carefully use a sharp blade. Twist the wire filaments together to make it easier to insert into the terminals.
Connect each conductor wire to the correct terminal (see image if you are unsure). Terminal styles can vary, but usually consist of a hole and a small screw that passes through it. Loosen the screw, insert the stripped part of the conductor wire into the hole and hold in place whilst you re-tighten the screw. Once all the wires are in the correct terminals, undo one of the screws that hold the flex clamp, slip the flex beneath it and replace the screw. Tighten until firm, but try not to over tighten. You can now replace the back of the plug securely and your plug is ready to use.