For a children's (fictional) story behind the annual lighting of the Christmas tree at Rockefeller Center in NYC, I invite you to: http://amzn.to/19iclpD
You will, I hope, forgive the slightly religious overtones -- underhanded though they may seem -- in this story. I was raised a Presbyterian. And while I may've shucked that corny skin many years ago, one's first years are formative.
A word of caution if you're a parent: you may want to read the story yourself before you choose (or not) to give it to your child. Some of the vocabulary -- even for me as the writer of the story -- was (and is) not current.