Even a novice can add electrical outlets to existing light switches already operating in his home. All it takes is a basic understanding of electrical connections, the right tools and materials, and a good deal of caution.
Step 1 - Turn off the Power
Turn off power at your circuit breaker panel, the most important step in connecting an electrical outlet.
Step 2 - Prepare to Connect Wires
Remove the wall plate and and screws that hold the switch in place. Pull out the switch, and locate the black, white, and bare electrical wires and the terminals they're connected to.
Step 3 - Install an Electrical Box
In the drywall near your switch, cut a hole that will fit your electrical box, and fasten the box.
Step 4 - Connect the Wires
Cut a length of Romex wire that will fit between the switch and the hole you cut, and strip the insulation from both ends, and connect your wire ends to the switch terminals, matching wire colors Then, connect the other end of the wires to your receptacle.
Step 5 - Finish
Attach Receptacle and Switch to their boxes, replace the wall plates, and turn the power back on