Adopting a pet is really easy. You can go to your local animal shelter where they have animals that were either neglected, abused, or just dropped off. They will let you look at the ones they have, and if you like any you have the chance to bring them into a good home. Of course most animal shelters charge a fee for adopting since that's one of the only ways they can care for these animals is either through donations, or adoption. Most will even give you a free bag of food to go along with your pet.
I think adopting a pet can be one of the most rewarding experiences. Although I have never adopted, I most certainly will in the future.