After deciding the route, mark and cut the holes for a new receptacle, switch or fixture using the outlet box as a template. Before installing the new box, use the hole to aid in running the new cable.
Often a wall receptacle from an upper floor can be used as a source for a new ceiling fixture below, but a switch loop must be run to a wall switch in addition to fishing the cable from the source.
This page offers some options for locating an electrical source for a new wall receptacle or a light fixture, and running the new cable required. To make this job easier, it’s best to have a second person at one end or the other of a new run, to sight the end of the fish tape and help guide cable. Also be sure to always turn off the affected circuits before working on household electricity.
Anything that will allow electricity to pass through it is a conductor. Metals are typically good conductors with copper being one of the best.