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How to wire electric lights?
easier than us here trying to describe it to you i would recommend picking up Black and Decker's wiring book. it has detailed descriptions with great pictures that make it very easy to understand.
or go to a google image search, or youtube search.
Add to the search what type of fixture / switch you are trying to install.
Where are you located? Wiring types and methods may vary a bit between the US and India or Southeast Asia for example.
More info needed, but first learn about basic wiring as suggested.