How could you describe the major themes in your own words?

There certainly is the theme of racism in the context of the 1930's Southern United states. Coming of age is another theme as we see Scout, Jem and Dill all mature through some pretty serious situations. There is also "doing the right thing" in the face of overwhelming opposition.

I can give you the link for it if you'd like

http://www.gradesaver.com/to-kill-a-mockingbird/study-guide/major-themes/