You just start.
And it will probably be awful, and derivative and cringeworthy. But you will practice, and learn, and more importantly learn yourself. You’ll get better and your progress will fill you with joy. And your failures will torment you. But in time it will become an old friend, a pool in which to pour your heart and reflect On everything you feel. And then you will find you are not just writing poetry,
You are a poet.
(Also, this was not supposed to be written as a poem, it’s just how I think)