Lots of factors go into this that we don't know. Your age, your income, your job/daily routine, etc.
As a blanket statement, I agree with others posters who have already said this, but there are only really two steps:
1. Eat less
2. Move more
If you can afford healthy food, get it. If not, eat less of the junk stuff. Are you LOTS overweight? If so not much change is needed to see a large impact.