Find something you can splint it with - ideally light and stiff, so aluminium, strong plastic....
Pad the splint a bit, then tape it to the wing to support it in the right position. I find that once I've splinted it and got it in a correct position, taping the wing to the body gives the best support. I use that bandage that's sticky to itself, as it doesn't pull feathers out, the better ones seem to cope with water ok. Obviously be as gentle as possible throughout.
Check her often, undo the bandage to the body every couple of days and let the air in for a few minutes. She'll mend and do fine.