How do you perform cpr properly? Is doing it on an infant or toddler/kid different from adult and older people?

Take the class. It's great that you are asking this question. CPR is different for infants and adults. It continues to evolve as we learn more. The introduction of aed's has made learning CPR even more important. The quicker you can get electricity to the heart the better. Take a class. Who knows when you might save a life.