Well, I can't explain all of the things you study in physics here. I can point you in some good directions.
I don't know how much math you have had, but if you intend to do quantum physics with mathematical rigor, you will need to learn all the way up to Calculus and Differential Equations. For this, I suggest you learn Algebra, Geometry, Trigonometry, Calculus, and Differential Equations in that order. Anything else you can pick up is great, such as Matrices or Advanced Geometry.
Understanding the quantum realm is easier if you have some chemistry and physics background. Taking a basic physics mechanics course (or just reading the textbook, as you seem inclined to do), then take a chemistry class, then an electricity and magnetism class. Things make the best sense in this order, in my opinion. You can do the mechanics course with just a geometry understanding and some basic trig, move into chemistry while doing calculus, and do electricity and magnetism once you have finished calculus, but you can explore these in greatest understanding once you have calculus completed.
Then you can move into the quantum physics.
The age of the textbook you use really doesn't matter until you get into quantum physics anyways, so you can go to used bookstores and get old textbooks for cheap (10-20$).