Then, with some of your classmates, read a few of them in front of the class. You'll find lots of movie reviews here written in haiku. At this site, you'll find a lot of words. You can drag them around with your mouse. Then use that idea to add more words.
Poems can be about anything.
They can rhyme, but they don't have to. They can be serious, or they can be funny. They can be short, or they can be long. Here is a very interesting collection of poems from people around the world. You can even send your own poem to them, and if it's good enough, they'll put it on the web site.