Help with dieting/weight loss?

I am 5'3" and 130 lbs. I am not overweight but I do have some extra chub I wouldn't mind getting rid of. I have really bad eating habits. xD My diet consists mostly of soda, cake, ice cream: mostly anything sweet. I will not drink water because I think it tastes gross, but recently I've been trying to down it since it's healthy and encourages weight loss. I also started walking to and from school. Would I lose a substantial amount of weight if I cut all the sugar from my diet and walked more frequently? I'm mostly concerned about flattening my tummy...so if you have tips about that, that'd help. Thank you. :)