I suggest you go to the hospital first for serious observation. Orthopedics ---- fracture is divided into comminuted, spiral fracture, compression fracture and other kinds of fracture. Before fracture fixation is to connect the fracture site before doing the fixation, some cases need to be fixed after surgery. Use different splints according to different parts. Read more books and cases on this subject.
Artificial respiratory masks, pacemakers and the like - common use in the emergency room you can go to see, you need to be familiar with the normal vital signs of the human body (heartbeat, respiration, pulse, blood pressure, etc.). These first aid tools are used to save lives, they can't be used as toys or you will miss a life!
You can start by memorizing those first aid points, such as Renzhong, Baihui, Hegu,,, and common sense of what kind of first aid is needed for what condition of the patient. Bless you!