How can I get a good education if I don't have money?

So I've been looking for ways to get a decent education online. I'm mainly looking to delve deeper into my field of study, Computer Science with a focus on Artificial Intelligence, and I also want to explore physics and mathematics. My university isn't the best in the world, so I'm looking for ways to improve my education. I really appreciate your attention and would be grateful for any advice. Congratulations to those at elite universities!