I am trying wire a motion Senior its has 3 wires coming out the back red white black

To connect a separate motion detector to a light fixture (and assuming the fixture uses incandescent or the newer twisted florescent light bulbs), the RED wire from the detector is attached to the black ("hot") wire from the fixture; the WHITE wire from the detector is attached to the white wire from the power source; the BLACK wire from the detector is attached to the black ("hot") wire from the power source. Sometimes the white and black wires from the power source are mixed up, reversed. So it is best to check to determine which wire is actually "hot" (shows voltage in a meter between the wire and the ground wire or the metal box the power wires come from). In general, a colored wire (often black) in the power source, if wired properly according to accepted custom, will be "hot" and 120v in US. The white wire in the power source is called the "neutral" and should be neutral with the ground wire and/or the metal box. If there is another colored wire in the power source (often red) and if it is not taped with some black tape (to indicate it is really a black wire), then it too may be a 120v. hot wire, but it may also be an 120v. hot wire that is 120v opposite the other 120v wire. That is, one 120v wire is 120v+ and the other is 120v- The difference in voltage between these 120v wires + and - is, hence, 220v. If you see multiple colored wires, it is also a good idea to check the voltage between them to know if you are dealing with a power source that entails 220v. In short, you want to know what you are doing, obviously for personal safety, but also to accomplish what you want... to properly connect the motion detector.