I am very much an amateur. Have completed a pre-calculous and a calculus course but have had little experience using them. My real agenda is to understand a number of physics concepts as expressed mathematically. I am looking for help when I get stuck. Also need help using a science computer. Like how to get two variables in a function -- like x2 + y2. I'm 72 years old -- retired. Mainly for philosophical purposes I want to deepen my understanding of things like relativity (special and general), quantum physics, entanglement, waves and things like that.