School me on wiring

Very first thing is to get a test light and a volt/ohm meter.
The test light is the kind you ground with a clip and touch wires with so it lights when touching a positive voltage source.
The volt/ohm meter tells you how much power is available and what the resistance of a circuit is.
Then there is continuity, which is testing to make sure there is a connection between one place and another and the volt/ohm meter also does this.