Pull cable to boxes and light Run a 14-2 NM-B cable (white, black, bare copper) from your power supply to the first switch location. If you're adding a 3-way setup to an existing situation, this ...

If you wire a 3-way switch wrong, you may be able to turn the light on from one switch, but not the other. It’s important to review how to wire a switch before attempting this project.

In some (all?) variations of a three way switch, either of two wires MAY be hot. if you are using Black/White wire, no combination is 'right'. It would be up to you to mark the white wire so ...