What is it that you exactly need help understanding? Either way I'll try my best to help.
It sounds like, for the first assignment, your teacher wants you to choose one of the prompts and write your typical high school essay on it. That's fairly self-explanatory; however, I won't put any words in your mouth. You'll need to do the work yourself.
I'm willing to bet that you mostly need help on the second one. The rules for a formal letter are really all about language and formatting, to which I attached a picture with an example. You just have to write some sort of complaint with the rules, presumably just to show that you know how to do it.