What happened to her? I can't even tell what that is a picture of.
She really does need to go to the vet if I were to just go by what I'm looking at, it definitely looks bad. Have you tried to see if there is a low-cost vet near you? Or possibly one that will allow you to make payments?
It must be very difficult when there are not veterinary surgeons near by, and costs of getting to them plus the treatment high. That said, the nature of this wound is difficult to see from a photograph and could be a puncture wound which can go deep in to the soft tissue. One of the biggest risks with puncture wounds is that bacteria can enter the wound site (esp if it has been a bite or claw injury) and cause infection deep down. Not only will this be very painful for your cat it is also difficult to see until it is very severe and can result in serious illness including blood poisoning.
Cleaning the area with boiled water which has then been cooled and salt added can help cleanse the surface area as long as the wound is open.
You must keep a very close eye on the wound and on your cat's general health and behaviour if you are not able to get them to a vet for treatment now. Even if the wound seems to be scabbing over and healing do not stop checking and being alert to your cat's behaviour as infection deep in the soft tissue can still be on going.
I really hope you see this wound heal and not further symptoms develop. Take good care of her and watch over her until you are sure all is good.