If you're able to, take the kitten to a veterinarian as soon as possible. Kittens need a series of vaccinations and deworming treatments, and they should also be spayed or neutered to prevent them from adding to the pet overpopulation problem. If you're not able to take the kitten yourself, contact your local animal shelter and ask if they can help. Many animal shelters have staff who are experienced in caring for abandoned kittens, and they will be able to get the kitten the necessary medical care.