Good health-tips after 4 of years of chips-eating?

So I want to become healthier after 4 years of eating chips and drinking coke on my couch. So I'd really appreciate health-tips, like how I'm going to quit coca-cola (replace it with something, I don't know..) And also how to tone the area right under my butt, there's a little ''bump'' under the butt which annoys me, haha.
Good health-tips after 4 of years of chips-eating?
Post Opinion