Your thesis is going to be related to the assignment you were given, but you don't want to repeat it word for word. Don't say: "Atticus Finch is a good example of social awareness, morality, social responsibility, and integrity." What you want to do is develop a more general statement that encompasses all of those items. How about something like "committed to doing the right thing"? Doesn't that embody all four of the concepts in your topic? You could probably come up with a better thesis statement than my example if you put your mind to it.
But first, you need to do some background work. What I would do first is make a list of the requirements your teacher has given you. It looks like you've got to deal with social awareness, moral choice, social responsibility, and integrity. As you read, think about the main characters in the story. A lot of them are going to be able to fit with the assignment: Scout, Jem, Atticus, Calpurnia, Sheriff Tate, etc.
As you read, jot down examples showing how each character meets the four criteria above. If you've already read the book, you can do this quickly be skimming. You don't necessarily have to do this with all of the characters I mentioned, you might pick a couple or even just one. I can tell you that the easiest and most obvious choice is Atticus, but that doesn't necessarily mean he's the best choice. Your teacher might be more impressed with your effort if you took one of the other characters.