Answer:
Since this question requires a description of your own school, I will give you an example of what you can write so you can make your own letter.
Explanation:
Dear friend,
How are you? I want to write to tell you about my new school. I am so excited to be here!
This school is wonderful, we have a science lab and a technology lab.
We also have a football field but as you know I don't play very well! But what I do well is swimming and we have an incredible pool for that!
I wish you were here and could enjoy this incredible place with me.
I miss you very much!
Best regards,
Sam.
Since the letter is for your friend, you can use informal language. And what is asked is that you mention the facilities of your school that, as you will see, I named several of them.
However, you have many more like libraries, basketball court, gym, dining room and many more. You simply have to describe the facilities that your school has.