Background
There was a frog that lived in a shallow well.

” Look how well off I am here ! ” he told a big turtle from the Eastern Ocean. ” I  am master of the water and lord of this shallow well, What more can  a fellow ask for? Why do I want to leave the well ? “

It was only until the turtle took the frog outside of the well  (or told the frog what were outside) that the frog realized how big the world was.

Meaning
It means a person who cannot see  the world or things in big picture

Examples

  • A son who was born and raised in a small place like Hong Kong told his father  ”I do not want to be a frog in the well. I want go t o a university in the United States to further my studies and see what life is like outside Hong Kong.”
  • A member of  Italki or LiveMocha wrote in his profile “I do not want to me a frog in the well. I am learning Chinese so that I get to know more about the Chinese culture and the people of China”.
  • A New Yorker laughed at a man from a small town “You are a frog in a well. You don’t know how big New York is.”
  • A teacher told his students “You must study hard and read more otherwise you will be a frog in the well.”
  • A person thought the bank of his country was the biggest bank in the world. He was told “You are a frog in the well. Don’t you know that the three largest banks  in the world by capitalization are Chinese banks”.