You need to spend time making some decisions and doing some planning for your composition.
It might be easiest to start with the location for your story. What is a type of environment that you enjoy and that you know well? You will be more capable of providing vivid descriptive details about the setting for your story if it takes place in an area like one with which you are very familiar, so model your fictional place after a real area similar to some real place that you like.
Depending upon the type of setting you choose for your story, perhaps next you could decide on some sort of unusual or surprising event that might take place in such a setting. If you plan to have your narrative take place at a tropical ocean beach, for example, your plot could involve: discovery of an item that has been washed ashore; the aftermath of a hurricane or tsunami; the challenge of making a living as a fisherman; the development of a small business resort. Pick an event that will be interesting to the reader, that you will be able to write about knowledgably, and that is plausibel for your location. Your plot outline will provide the basic events that occur as the action of the event unfolds.
Your character, then, becomes the person who responds to the situation you've created in the environment where you have placed your story. You'll need to decide if your character is your age, older than you, or younger; is this person very organized and capable of dealing with whatever is happening in the story or is s/he frightened/ignorant/shy - or in some other way challenged by the situation being presented? You can decide how your person goes about addressing the situation, what problems are encountered (and how they're overcome) and what surprises are revealed.
A narrative tells a story. That's what you're doing - creating the story of a certain person, in a certain place, dealing with a certain set of circumstances. You get to pick the specifics!