The theme is a fable or moral. It is suppose to teach us something.(Teaches us a lesson in or about life) You might write a story about a student picking on smaller students in a school. As the story develops, he finally picks on a smaller student who fights back, thus teaching him to be kind to everyone.
The theme is the behavior of the characters in a story. In fiction, the theme is to teach or persuade an opinion to someone.
You want to be aware of actions or behaviors that are repeated again and again in the story. Be sure to be aware of all the details in the story, and which set of details have the most important meaning.
Remember that the theme, plot, and structure must all be presented when writing a story!