The main thing with these if you can't get to your vet is that they remain clean and that she doesn't scratch at it.
Depending on where it is on the neck you can try using a tshirt of some sort to cover the wound. You can also clip the hair so that there isn't hair going into it and irritating it further, this will also help to keep it clean. Then clean it two times per day with some water and a paper towel and keep debris out of it.
I hope that helps. If you have any further questions feel free to ask!