try to experiment. It's okay to make something bad, when you're just trying. Forget all you know about the 'rules' and just do it! If you find this very hard, try to cut out pieces of paper with the words bridge, verse etc. Or, write the verse and so on, and then write it on pieces of paper. Then, just draw a card, and put it together. Don't think about what you can and can not do. It's YOUR song, and you can do what you want. At some point, you're going to have something completely different. You can end up with intro, verse, verse, bridge1, verse, chorus, verse, bridge2, chorus, outro.