If you cant take the dog to the vet then try this, If the torn skin is still there get some one to hold the dog while you stitch it back up, needle and cotton will do or super glue, i kid you not, i have used this method on my racing pigeons, then antiseptic powder to dry the wound (available from any decent pet shop), then cover the wound with absorbent cloth from any first aid kit and bandage over this, it does not have to look pretty and you will have to change it every day, and keep giving antibiotics until there is no redness (infection)around the wound.
Hope this helps!