What is the best way to process or determine theme? me

1. What does the book mean to you? What is the life lesson you can get from the book. 
2. What changes happened to the characters? For example someone may have been mean but ended up becoming a forgiving person, thus the theme would be generosity.
3. What was the conflict and how was it solved.

Hope this helps :)

Not really sure but wow ur work is hard