I am a high school student. I looked up Special relativity and grasped it pretty easily, without needing to learn any new math. But when I tried to read about general relativity, I was immediately confused by all the math, equations and notation. My problem is that I have no idea where to begin to progressively learn about general relativity. So I would really appreciate it if you could advise me on what (mathematical) topics to look up on before I continue, and preferably in order (for example learn topic 1, then topic 2, etc). Thanks in advance!