Put words on a page. Write about what's going on. Tell your story your way. Read and watch other artists for inspiration. Keep a notebook. Perform.
When you are getting started with poetry you can begin by free writing. Free writing is just writing whatever comes to your mind ("stream of consciousness"). Anything can be written on the page; there's no wrong or right answer.
Set a timer for 10 minutes and write for the whole time, never lifting your pencil off the page. Think about things going on: in your life, in the world or in your community. It can be as simple as making a list, like "A list of people I miss."
Keep working to find and tell your own story. Start thinking about your life experiences in ways that you can portray in your writing.
For example, if your experience is that your walks home from school aren't safe, then a unique way to approach that story could be to list 10 ways to protect yourself while walking home from school.
Check out more writing prompts from Young Chicago Authors for some more ideas.
Find other writers and artists who you can learn and draw inspiration from. Pick two of their poems that you really like. What do you like? What are they doing really well? Compare and contrast those pieces and write a poem inspired by those texts.
Keep a notebook or journal of ideas that you have about writing and the stories that you want to tell. Use it to remember the writing, art, and performances that you want to learn from or write about.
Focus on the performance of your poetry – what does your voice sound like for each line?