Learning to ride a horse is not something to learn by yourself! You may not need to take formal lessons, but you should have the guidance of someone with experience.
The reason for this is that you need to learn the basic "language" to communicate with the horse. For example, there are different ways to tell a horse which way to turn (neck reining, direct reining, leg pressure, weight). This is not something you would instinctively know how to do. Since you communicate with a horse via a metal bit in its mouth, you could even accidentally cause it pain if you don’t know how to use the reins properly.
Also, you need to know how to react safely in an emergency. Would you know how to stop a runaway horse or do an emergency dismount? These are things that someone needs to teach you.
You’ll also need guidance in tacking up the horse (putting on its saddle or bridle). For example, if you don’t saddle the horse properly, the saddle could shift and you could fall off. Or it could rub the horse and give it a sore.
Once you know the basics, you can expand on them yourself. But when you first get started, you will need some guidance. Good luck!
Barb Nefer