Suppose you are a writer, how to begin your writing? Where should the world be put in the text?

I think designing the episode is the first thing to start a writing. After that you should arrange some characters to support the episode and try to make conflicts between the characters. Furthermore, social circumstance should be implied into the specific words and episodes, which can express the original intentions of a writer. The world of the text should be put into the specific words, acts, habits and clothes of characters, the buildings and other circumstances.