Treating broken bones and sprains is done by a medical professional. If you suspect a child has a broken bone, call emergency services immediately.
Do not move the child unless they are in a dangerous area. If there is blood on the wound, stop the blood using a clean towel.
Apply cold packs or ice wrapped in cloth, and keep the child laying down until medical services arrive.
Accidents will happen all the time with children which is why it is important to attend a paediatric first aid course if you are frequently around children and want to ensure the safety of the little people in your care.