How do I naturally get rid of my pimples on my face, back and chest?

Following the guidelines here and generally taking good care of yourself (eating well, getting enough sleep, exercising, managing stress well - there are articles on all these topics here if you need them) can help. Practice good hygiene, avoid touching your face, wash your clothes and pillowcases/sheets regularly, use a natural laundry detergent if you can, and avoid using dryer sheets or fabric softener (they can aggravate acne for some people). But don't be afraid to also use an acne product if you need it. Sometimes the acne won't go away completely by 'natural' means no matter what you do, especially if you're young, since your hormones can just be too out of balance at that age.