That really depends on how old the kitten is and what state of health he or she is in. Consider a veterinary examination to help determine the kitten's age, exact care needs or if any health problems exist. If the kitten can eat and drink well on its own, he or she may need only routine kitten care (safe environment, kitten food, water, toys, bed, litter box, veterinary care, etc.). If the kitten is too small to eat and drink well unassisted or does not have the eyes open yet, you will have to act as a replacement mother. Extremely young kittens need to be fed kitten milk replacer according to the manufacturers' directions as often as every 2-4 hours, depending on age. They may require a safe heat source, such as a heating pad and an enclosed nest area (like a box). If a heating pad is used, be sure to follow all the manufacturers' safety instructions and only heat about 1/2 of the nest area on a low setting. The kittens can regulate their body temperature better if allowed to move between warmer and cooler (room temperature) spots in the nest. Extremely young kittens cannot pass stool and urine by themselves. They need gentle rubbing in the genital areas (with moist warm cotton balls or a very soft moist cloth) to help them pass bodily wastes. This should be done every time the kittens are fed. Any stool or urine MUST be gently, but completely, cleaned off the skin to avoid potentially severe skin rashes and even blistering from body wastes. Numerous books and other resources exist to help you.