Some of you guys are just being plain dicks to the OP.
OP, as others have said, ditch the soda, it is the worst thing. If you drink it for the caffeine to give you a boost try black coffee. Second, as others have mentioned, walk, do just do the I'm just chilling walk, walk like you about to be late to something. Walk twice a day, 30 mins each time, to start off if you can't do the whole walk at the brisk pace, try walking half of the 30 mins hard and then the other half calmly till you can and work your way up adding a min or two each day or two till you can walk briskly the entire time.
Cut back how much you eat but don't do it drastically quickly cause otherwise you will be miserable and will probably cheat. For example just take a little bit less then you normally would, like if you eat chicken nuggets and you normally 10 for a serving plus sides, try taking just 8. Do it in baby steps once you get use to the smaller portion do it again. It will take sometime but you need to not feel like you are super hungry while doing it, a bit of hunger will be expected but as long as it is tolerable you'll eventually get use to the new amount of food and you can repeat the process.
One more thing, drink lots of water, it is your friend. Try to kick all the other stuff, if you drink milk go to skim or work your way down to it. Water is also a decent appetite suppressant that can help you as you are lowering the amount you eat to offset some of the hunger you would feel.
Those are all easy things that can be done in steps, think of it is like that patch system for smokers. You are easing down from what you are use to till you can quit all together (quit in this case is a reasonable calorie intake each day)