Yes, you have to get a textbook. Most textbooks are written to be reliable. Mathematical topics truly are very technical. If you are aiming for concepts of "PreCalculus", then you should have no trouble finding good, very helpful, reliable books. You could try examing some "Dummies" book if you find one, maybe by 'check out' from a local library and see if it helps you.
When you study from a Mathematics book, you are not reading in the same way as if it were a novel of a story. You are trying to understand concepts and learn skills. This requires a much different kind of effort than for a fiction or nonfiction story. You might spend 5 hours to cover 3 pages of a Math book; while in 5 hours of a novel, you might cover maybe 50 to 60 pages... or more. Often you must reread those same 3 pages of a Math book as much as 8 to 10 times. You also must try example problems and any guided practice problems to help you explore the Math concepts and develop your skills. Yes, the Mathematics is dense and technical. The books usually include some discussion about the topics presented... discussion and explanations. Those discussions are usually both reliable and efficient (again, I say this about good Precalculus, Intermediate Algebra, and Trigonometry books).