Depending on the size, condition and location of the wound there are a few things you can do.
If the wound is a tear in the skin, like a laceration, but the sides meet, you can sew or tape it shut. If you sew it, clean the wound with a sterile saline rinse, then with a solution like Betadine, you can rub a little Neosporin w/lidocaine on the wound edges before you sew them back together with a sterilized sewing needle and thread that was soaked in Betadine solution. If it's possible to use a piece of athletic tape or a butterfly bandage to keep the edges of the wound closed, that may be an option.
If the wound is a missing patch of skin (with or without minor muscle damage below the skin), you will want to put sulfur powder (sold online, at natural food stores, garden centers, feed stores) or WonderDust (sold at
Tractor Supply in horse section) on it. These are antibiotic powders that help the wound to stay dry and to heal.
Your chicken may need to be confined to the house or other warm area for awhile until her wounds close, which will of course depend on the size and severity of the wounds. Keeping her in a place where she has heat (from a heat lamp if necessary), electrolytes in her water (electrolytes for poultry, like Sav-a-Chick), food & treats (melon and grapes help keep her hydrated), will help her body to repair itself. When she is healed up enough to join the flock, a modified baby onesie or a hen saddle (just something that covers the naked or scarred area) should keep her safe from picking. I have used the sew method, sulfur powder method, and have put saddles on my hens & have had success.
Hope this helps!