Then you must get some supporting information. Here are some tips by Lucille Renwick on how to come up with a topic and interview people.
Reporters usually get assignments from their editor.
But the best reporters also come up with ideas for their own stories. They look, think, ask lots of questions, and talk with LOTS of people. One story I wrote involved kids living with their grandparents instead of their parents. The idea for this story came to me indirectly. While interviewing somebody for a different story, I learned about a woman who was raising her grandson.