The Net Promoter Score

I think the best way to appreciate the NPS (net promoter score) is through a simple exercise. So, after you read the article, pick a brand with which you have some familiarity, and ask at least ten people these two questions( these answers can be made up, no need to ask 10 people unless want to just need info for paper:
How likely is it that you would recommend this [brand name] to a friend or colleague?
Why do you feel that way?
Your respondents should be familiar with the brand too.
Then, calculate the NPS, analyze findings based on their answers to the second question, and make strategic recommendations about how to improve customer loyalty.
You need to realize that this is not how a survey should be done because your sample here is not a scientific one.  Scientific survey processes and the associated data analysis require specialized training that many managers likely do not have.
However, I think it is useful for you to do this simplified exercise so that the NPS concept can be better understood.  
In your submission, you need to include the answers to your questions from every person you surveyed.  Do not just have a summary of the answers.  You may put these individual answers in a table.
Have fun!