do cardio like mentioned above, but if you have not done it before or in a long time then start off slow.
You want to get your heartrate up to like 70% or so of your max heart rate... I did a quick search on google to find a max heartrate definition and I found this
Males: 214-(0.8*age). So for instance I am 38, so it would go like this... 38 * .8 = 30.4, now subtract that from 214 and you get 183.6. Aout 70% of that is like 128, so I would shoot for roughly 130 or a little higher for at least 20 miunutes. they say that the real benefit happens after 20 minutes.
BUT, I would say to start slow meaning shoot for a lower heartrate for say, 10 minutes for a few times, then go longer till you can do 20 - 25 minutes, then start bringing up your heart rate to the 70% or so amount gradually.
You can't make your body loose fat in any certain area in particular, all you can do is loose the fat and the body decides where it comes off first.
Definitely find an alternative for the soft drinks. If you can go without them for a while, you will eventually get to where they taste funny and you really dont want one any more.... that is what happened to me. I have one every once in a while, but I never crave them at all.
Gaining muscle will also aid you in loosing fat - the more muscle you have , the more calories you burn just sitting there doing nothing at all. So for a longer term more permanent fix you could add to your muscle mass.
Good luck! and I hope that was some help.