If you don’t want to study in depth, you don’t need to learn a lot of music theory. The first time you learn guitar is to use six-line notation. As long as you can read six-line notation, it’s very simple and easy to learn. But it’s very difficult to learn well. You can buy a book for yourself to learn guitar. Then you can practice guitar yourself. It depends on how hard you practice it. Quick, beginner, two hours a day, because you can’t absorb too much practice.