Nobody can tell you what to write - you must write what is in your own heart and mind. Copying what someone else has written leads to dull, boring writing that is not going to help you learn how to...
Write about something that one of your friends maybe does. For example, I have never seen my best friend cry before. and we are closer than two peas in a pod. :) So I just recently wrote a poem about...
Write about something you feel deeply about. Such as success, failure, a person that has made an impact in your life, an upcoming event, a favorite hobby.