If you are in 9th grade, I am assuming you are reading a retelling of The Odyssey in your literature book.
In that first section, Homer calls on the Muse of epic poetry to help him tell the story of Odysseus. A muse is like an inspiring spirit that can get into a person and help motivate them to do what it is they desire to do. For Homer, it's tell a story in the form of poetry.
Here, Homer reveals to us the purpose for telling his story, so that we can all know of the great character Odysseus' traits and how he used them. He tried to get his men back to their homeland, but the men did not always listen to their leader and this was their downfall. Already, in the invocation, we are learning about what the storyline will look like, what will ultimately happen to the men, and we learn a lesson - obeying authority might be a handy tool in life.