Ouch, don't drink pop when you are thirsty. When you are really thirsty, that is the time to drink water. Since if you are thirsty, ANY liquid will do. Most people don't drink enough water because it's tasteless and they can't choke down a gallon a day (about what you should be drinking). So make yourself drink water when you are thirsty because that is one of the few times you won't notice how tasteless and blech water seems to you.
You should work to eliminate pop from your diet totally. If you keep working towards drinking only water and a few other (occasional) beverages-- after awhile you won't mind the taste of water.
As for losing weight-
1. No special restrictions on your diet. Don't aim for only fats, only carbs, only whatever. Simply aim for eating more natural foods over processed foods.
Don't waste your time figuring percents of fat or carbs etc. If you eat more natural foods, it won't be a problem.
2. Exercise more. (duh) If you are looking to burn calories, that means aerobic type exercise for 30-45 minutes, 3-5 times a week. Target heart rate should be (220 minus your age = your peak heartrate. Figure out 65-85% of that peak heartrate. That is your target area that you need to be in for those 30-45 minutes)
If you are a beginner, you might only be able to do 10 minutes at that level. That's fine. Do that for the first 2 weeks, then begin to increase it. Go up to 15 minutes for a week, then up to 20 minutes. Whatever you can do. But keep to the routine. If you are a beginner, 3 times a week is probably best since you won't see much more benefit if you went to 5 times a week so soon. Being that you may be terribly out of shape, 3 times will give you lots of benefit. You can increase it later as you become more fit.
3. Find some exercises you like to do. For fatties, I think running is not a good idea. Way too much stress on the knees and ankles. Things like swimming or bicycles can be better options for cardiovascular exercises that don't stress the joints.
It's important to find something you like to do since that will be more likely that you can keep to it. If you truly hate walking or swimming- you probably aren't going to stick to it.
4. Eating several smaller meals through the day is a good idea. It keeps your blood sugar levels more constant and it also keeps your metabolism more constant.
Examples are eating a regular breakfast at 6 am, then a snack at 9 am, a light lunch at noon, a snack at 3 pm, and a regular dinner at 6 pm.
Snacks can be fruit, nuts, or some other type of natural foods. NOT junk foods.
Those are some basics for getting yourself fit and weight under control. Also, remember to think in long terms and not look for instant short term gains. You didn't get out of shape over night and you sure aren't going to get in shape that quickly either.
Good luck.