Summarize the following:
An in-home power extender has 2 receptacles that connect behind your wall and provide power to an additional outlet. When you plug the lower receptacle into a wall outlet, it will provide power to the upper receptacle that you can hide behind the TV. Look at an electronics store or online for a power bridge that has built-in power connectors so it’s easier to wire. You can buy in-wall power extenders from electronics stores or online for between $40–100 USD. Hold the upper receptacle against your wall in a spot that your TV will cover once you hang it. Use a pencil to draw an outline around the receptacle. Place the lower receptacle straight down from the first one so it’s at least 6 inches (15 cm) off of the ground, and draw the outline on your wall. The lower receptacle will be visible on your wall, but you can easily hide it behind a shelf or entertainment center. Make sure both receptacles are between the same studs if your wall has them so it’s easier to fish the wires. Push the blade of the saw or knife into your wall so it breaks through the other side. Use a slow and straight sawing motion to slice through the drywall along the outline you drew. Pop the piece of drywall away from the wall after cutting it out. Repeat the process with the other outline that you marked.  You can buy a drywall saw from your local hardware store. If you have brick or concrete walls, hire a contractor to cut through it for you so you don’t cause any additional damage. Feed a fish tape, which is a tool with a long line used to run wires through walls, into the upper hole and push it straight down. Pull the fish tape out from the hole for the lower receptacle when you see it. Tape any HDMI, AV, or network cables you want to plug into your TV to the end of the fish tape, as well as the power connector cable that’s attached to the back of the lower receptacle. Pull the fish tape up through the upper hole to pull the wires through. Make sure the AV cords extend out about 3 feet (91 cm) from each hole. The number of cables you pull through depends on how many devices you want to plug into your TV. Usually, you’ll need at least 1–2 HDMI or AV cables to attach a cable box or media player. Locate the power connector on the back of the upper receptacle and line it up with the connector you fished through the wall. Push the connectors together to secure them so electricity can run between the 2 receptacles. Feed the power connectors back into your wall once you plug them in. You do not need to turn off power at the circuit when you install an in-wall power extender since you aren’t connecting it to any existing wires. Look for the holes in the receptacles that have rubber or plastic guards surrounding them. Push the ends of the AV cords through the back of the receptacle so they go through the hole in the front. Repeat the process with the other receptacle so the wires extend about 3 feet (91 cm) out from each side. Be sure to put the cords through the receptacles before you screw the receptacles in, or else you won’t be able to pull them through easily. Push the receptacles into the holes so they’re flush with your wall. Place the screws into the holes along the outer lips of the receptacles and screw them directly into your drywall. Be careful not to overtighten them or you could damage your walls or the receptacle. You do not need to pre-drill holes before screwing in the receptacles.

Summary:
Get an in-wall power extender. Trace the outlines of the power extender receptacles on your wall. Cut along your outlines using a drywall saw or utility knife. Fish any AV cords and the power connector between the holes in your wall. Plug the power connectors from the receptacles into each other. Push the AV cords through the holes in the receptacles. Screw the receptacles into your drywall with a screwdriver.