Themes that can be found in The Hunger Games are:
Love sacrifices
Love doesn't die
All people are evil - yes all
Girls can be strong
Bravery
We cannot get rid of what we've done in the past, no matter how
much good we do to make up for it it will still hunt us.
These are the ones I can quickly think of. I'd like to encourage
you to read the books and try to find some themes yourself. Its
quite a magical experience :)