iTutor Math Updates

Hi there, Does anyone have any advice on what subject I should google to improve my maths? My maths skills are around that of a 14-15 year old high school student. I have looked up and learned the following: Fibonacci sequence Prime numbers Sets Unfortunately, I am not really sure why any of this is relevant. I want to learn maths because I want to come up with my own formulas for things someday. I am also interested in probability. I don't have access to any textbooks or a library. Any advice on things I probably don't need to learn would be appreciated.