If you teach yourself, find a book on this subject, not too old, because there are so many theoretical knowledge of digital and analog electricity that everyone speaks the same, and then study it carefully from beginning to end and understand it all. As long as you insist, there is absolutely no problem. If we can build some small circuits and measure them with measuring instruments, we can understand them better and remember them better. The most important thing is to stick to it, don't give up halfway, you will forget it after a long time, and you will learn in vain.