Can't you access the video I posted? It shows how to splint a joint. You splint it to make the joint immobile. She will not be able to bend the joint or the fracture site if properly splinted. Practice on a stick you've partly broken so it will bend. Wrap padding around the fracture on the stick then wrap elastic wrap around that. When you're done, the stick should be straight again and not bendable.
That's your goal with a broken leg bone, even if it's at the joint of the foot and the shank. She will probably be able to walk on it after you splint it. It should stop hurting if properly splinted and immobilized so it won't bend. Yes, use popsickle sticks or tongue depressors. Padding is essential. If you just wrap it with bandage, it may still bend and that isn't desirable since a hairline fracture can fracture the rest of the way.
If there's no swelling, it's possible it isn't fractured or if it is, it's hairline.