When you write a buisness letter how do you write it?

[JeXx]

My teacher didnt really explain how to write a buisness letter and he wanted us to write the body of it (8 to 12 sentences) about this contest where when you send in something you have to pay 20$ and either your against it or for it and you have to give reasons (though it sounded more like an opinion letter what he was describing but he said it was a buisness letter) so as a buisness letter can i say for example: The 20 $ fee for this particular contest shouldn't be needed. Many citizens will not have the chance to participate, either for poor-income or total homeless-ness (i dont know if thats a word but you get the idea right?) and in a buisness letter can I use the words: "I" and "You" and stuff thank you