You should start off with talking about an few female athletes that are famed around the world but don't make it too long.
<span>People with a casual interest in astronomy is the audience of the book by Ball. This is because the book is all about Great Astronomers. This book can inspire people who wants to discover things about astronomy and those people who want to become one in the future.</span>
It would be too obvious for me to write the entire letter for you, but I'll include a list of points that you could include in your own writing style:
* Thanking Lee for his letter, and saying that you are happy that he is having a good time.
* Telling him roughly what you're studying at school (without being boring).
* Write about what you would like to do when you leave school.
* Finally, say that you miss him a lot and look forward to hearing from him soon.