Electricity powers everything from lights to laptops and appliances, so having an outlet close to where you want to "plug in" is essential. It's not too difficult to add or replace an outlet, and knowing the basics of how to hook up one up is a good skill to have.
Make sure the electricity is turned off. Do not start until you are absolutely sure the electricity is off at the outlet and circuit you're working on. If there is an existing outlet on the same circuit, plug a lamp into the outlet, then shut off the breakers in the panel box one at a time until the light goes off. Leave that breaker off and turn the rest back on. If there is no existing outlet or none of the breakers turn off the circuit, shut off the main breaker for the home. Once the power is off, lock the panel box and make sure everyone in the home knows not to touch the main panel until you are finished with your project.
Remove the old outlet, if there is one. Remove the screw holding the cover plate and take the plate off. Loosen the brass and silver screws on either side of the outlet and disconnect any wires (there may be two to six depending on where you outlet is located on the circuit and the age of the home).
Look at the premounted box where the outlet is going to be installed. Locate the circuit wire, which should be running from the main panel to the outlet box. (If there is no wire or box, have them installed by a professional.) The circuit wire should be composed of three wires: a black one (hot/power), a white one (neutral) and a copper one (ground). If all you see is one thick white wire, without a "cut" end, it may mean that it is between other outlets and you will need to cut the wire in half to make a break in which to install the outlet. If there is a cut end, it is likely at the end of the circuit.
Strip a few inches of the white sheathing or covering that surround the internal wires, using a cable ripper or utility knife to make a slit in the sheathing and peeling it back from the wires. Trim the loose part off. Use a wire stripper to remove about three-quarters of an inch of the colored insulation from each wire, then use needle-nose pliers to bend each wire in a hook shape. (If you have removed a pre-existing outlet, the wires should be ready for use.)
Attach the wires if the outlet is at the end of a circuit. Take the prepared green (or bare) wire and place it under the green screw and tighten. The wire should wrap around the screw securely. Next, place the black wire under the top brass screw and tighten. Then place the white wire under the top silver screw and tighten. Make sure all wires are wrapped around the screws and not sticking out or touching other wires.
Create a "pigtail" if your outlet is between other outlets. A pigtail is a short piece of ground wire about 4 to 6 inches long. Hold one end of the pigtail and the two other ground wires together. Screw on a wire connector to join the three wires. Now put the loose end of the pigtail under the green screw and tighten. Next, place the two black wires under the two brass screws and secure. Then position the two white wires beneath the two silver screws and tighten. Check that all wires are wrapped around the screws and not sticking out or touching other wires.
Position the outlet in the box and fasten with the two screws. Using the flashlight, look into the box and make sure no wires are protruding or twisted sharply. Also check that the wires are still secured to the sides of the outlet. Lay the cover plate over the outlet and use the screw to affix. Return to the main panel and turn on the individual or main breaker. Go back to the outlet and using a circuit checker, plug it in to make sure the outlet is properly grounded and working.