This diagram shows two switches in the same box with two separate 120 volt sources. Three-wire cable is supplying the source for both switches with the black and red wires going to the bottom switch terminals. The black wire from each light is connected to the top terminal of their respective switch. The white and ground wires are spliced to run to each light fixture.
This diagram illustrates the wiring for a circuit with gfci receptacles followed by a light and switch. By connecting the switch to the load terminals on the gfci, the light is protected against ground faults as well.
The black cable wire is connected to the top terminal on the switch and spliced to the black and blue wires at the fan at the other end. The neutral source and ground are spliced through to the white and ground connections at the fan.
In these cases, it should be wrapped with electrical tape to mark it as hot. The ground wires will be green and/or bare copper. The ground should be spliced with a short piece of wire and connected to each device and outlet box that has a grounding terminal. In these drawing the brass colored terminal represent the hot side of the device and the silver colored terminal represent the neutral. Ground wires and terminals are in green.