How do I add a proposition to the ballot? Your opinion on taxing on soda?

It's too late for this election but I was thinking it wouldn't be a bad idea to start taxing soda. The rampant issue of obesity is weighing on the health care system from everyone, and even if you can't afford anything but junk food, there's no reason you should be drinking soda. People drink soda like water here, even though it really should be a once in a while type of drink (once or twice a week). We tax cigarettes and alcohol as luxury goods which are deemed unhealthy to the individual and society as a whole in large doses, so why not soda? How do you feel about taxing soda? Also, how do I go about making it into legislation?