Question about evolution...?

Ok so all my life I've been taught about God in a Christian perspective. I know close to nothing about evolution and although I know quite a lot about Christian beliefs, they have no bearing with me. Correct me if I'm wrong, but I've noticed that both evolution and Creationism have no reasonable explanation for how everything got started. What I've been taught is that somehow God magically appeared (although from what we don't know) and made everything in a week and from there things just took off. I don't know what the theory of evolution says about how the first organisms came into existence, but science (or, at least, my high school biology course) has taught me that everything comes from something. There is no such thing as spontaneous generation. So could you please explain to me what evolution says the first living things came from? Not how things evolved, but how they originally formed.