Answer:
Ff you find a bird with a broken wing, you have two options;
1.)take the bird to an area that you believe to be almost predatorless, and leave it there in a small area.
2.)take the bird and place it in a rabbit cage or something similar. Keep it warm and leave food and/or water near it. Then contact your closest pet help center or vet.
You cant realy mend it as it is a natural thing.