Charity in Jewish law

“The Moral Obligation of Tzedakah: Exploring the Role of Charity in Jewish Law”

I have to write an essay on charity in Jewish law. The answers you will answer will be; is charity a duty of justice as a Jew. The other question will be who’s money is it? Is it gods or is it mine? Did god put it in my hand to give out or I earned it all by myself?