Tell how the plot events and the authors’ use of literary devices help to support your ideas

what does this mean

This means that you should explain how the events in a story and the literary devices the author uses help to develop the ideas or themes you are discussing. For example, if you are discussing the theme of determination in a novel, you could explain how the plot events where the protagonist overcomes obstacles with perseverance, and the author's use of symbolism to represent determination, help to reinforce your idea about this theme in the story.