If you just want to play and sing, you can learn all the C chords and cover a lot of songs. By the way, add a tone sandwich and ask where to start learning? Go straight to study C D F AM tuning? The usual chords in C, Dm, Em, F, G, Am, AM7 are only F chords, which can cause you to tangle. Seriously put these chords in place, and after a week, you should be able to play 40 BPS. Remember a very slowly, you may not get obvious results on the first day. Practice for 20 minutes. If you feel overindulgent, practice more. After you sleep, you will find that it will become much easier. You don’t need to force yourself at all. If you feel uncomfortable, remember to stop, or you will be nauseous. At first the fingers were not feeling well.