There are 2 diagrams below, the first one is a diagram of how to wire 3 switches to the same light.  You use a combination of two 3-way switches with a 4-way switch in between. 
The second diagram shows how to wire 4 switches to the same light by adding another 4-way switch in series.
You can [...]

This is a typical diagram of how to wire a light switch.  There may or may not be a power out line that feeds something else in the circuit, or there may be more than one power out line, depending on what was handy for the electrician at the time.
CAUTION:
DO NOT EVER WORK ON LIVE ELECTRICITY!  [...]