What do I have to do in order to petition the school uniforms?

Everyone has their own opinion. I am from a pretty small town, and I think it's wrong. Our school is known for it's traditions amd for being humble and almost everyone is against it. We have to buy our uniforms, which are polos. I used to be morbidly obese, and I lost 59 lbs, and it blows that my first year of high school, my entire new sized wardrobe will be polos cause I can't afford to buy a bunch of polos and normal shirts. I hate this so much. It's depressing. I'm also still insecure in my arms, cause there's still flab from my weight loss. I am not going to do this. I'm writing a persuasive letter, and I have other friends doing the same with me. I now want to do a petition, but how can I do this? Who do I call? The school board, the mayor? And where Do I get the paper? Is there a special kind they will give me or do I make it myself? And what are the rules? What type of petition would this be defined as? An informal one? I am also getting parent signatures of course. I know I need a opinions that arent too bias and provincial. Thank you(: