A narrative means you're telling the story about something. Certainly, most people find talking about themselves and their experiences interesting, so that's an obvious possibility, but the main thing is to identify some subject that you will enjoy recording.
If you've seen a great concert or athletic event, you could tell about the anticipation, preparation, actual event, and the memories afterward. Recording the story of a trip you've taken could make for an interesting tale. If you want a challenge, write your poem about an argument you've had with someone - lots of descriptive vocabulary for all the emotions that came out!