Okay, so you have to describe what you like about your school and what not. That’s the first point. Here you could include anything that you like, for example if your school is modern, uses new technology, is well organized and structured, the teachers are supporting and friendly.
Then I would include what you don‘t like. On my school a big issue was for example the organisation, too many extra projects which lead to heavy workload, the toilets were incredible bad and with some teachers happened the same. If you could give me any points maybe, it will be more easier to write down a structure and tense for you
Then you have to describe how your ideal school would look like. Here I would put the most effort into, because there are many possibilities. For me for example my dream school would be very new and modern, using the newest technology, iPad or Tablets for students instead of handwritten notes, more supporting teachers... better opportunities for clubs and hobbies, maybe a school park to sit down.
From what I have understood you should write that like a blog, when you tell others about your experience.
In the introduction I would recommend you to say first some facts about your school, where it is, how it looks like, how many students they have...
So maybe you could write down some notes, what to include for each point and then post it here, it will make it more easier for us to help you, as we know what you like/don‘t like and what your dream school would look like