A newborn goat will need more than just cow milk from a store. If it has been rejected by its mother at birth, it will need you to provide it with colostrum. It must be given this within twenty-four hours of being born if it is to survive.
You should warm some cow milk and then put it into an ordinary baby bottle with a teat to feed it to the kid. Make sure that the bottle is clean and sterile before doing so. Make sure that the milk is not hot, but gently warmed.
You may wish to give the kid goat’s milk if this is available, but they should manage fine on cow’s milk. It is worth being aware that cow milk is slightly less fatty, so your goat may struggle a little to gain weight.