I would just bandage her up, if the wound is open. Even if it doesn't look good, it protects her from her puppies. Other than that, try to keep her still and rested. You may want to gently clean the wound and follow the directions you were given, still.
Keep her inactive. If it opened it was due to licking or to much activity. Do not wrap it, that will just cause a breeding ground for bacteria. I'm sure your vet has a emergency line for advice or after hour care.