Motorized Wheel Chair Source

First you need to understand that you need to burn the fat over your abdominal muscles to see your six pack. After that it depends on exactly what you're eating (you should try to eat mostly lean protein and veggies if you're trying to tone up) and how often (you should try to eat ~5-6 times/day to speed up your metabolism. Now to answer your question:
To get abs you need a proper balance of good eating, resistance and cardio excercise, and sometimes supplements. You need to add resistance excercise as that is the best way to reduce fat (muscle burns fat/calories) and change body shape.
Different people hold fat in different places and that last little bit of fat is usually the hardest to lose. There isn't any definitive way to 'spot' reduce body fat but here are some things I have found useful (to get a lean flat stomach and get 'abs'):
- Do sprint repeats. It's plenty warm enough to do these outside so that's good. Jog to warm up (~1/2 mile). Then do 8 sets of repeat sprints (start with ~100m and gradually move up to ~200m as you get in better shape). Basically you sprint all out, then slow jog (really slow) back. Repeat 8 times. The first one you want to go only ~3/4 speed since your body will still be warming up. Make sure you stretch afterwards as your hamstrings will be sore the next day (especially after the first time).
- Resistance training: go for more reps (less weight), try drop sets, try circuit training. All of these are useful for getting more lean(and as a result will burn fat off your abs). Remember the more muscle you build, the more fat you'll burn (and you won't be big and bulky either).
- Ab ball: do a lot of exercises using one of those ab balls...they work your core in every exercise. You can also do actual ab target exercises (twists, crunches, etc.). Get a trainer at your gym to show you some. Or you can get the CoreSecrets (ball/video) for ~$10-$20 online (just google it)
- Oblique exercises (twisting). Do a lot of these using the ab ball: sit on the ball hold a 10 lb weight and walk your feet forward. 'Lay down' and with the weigh above you twist to one side-up-pause-twist to the other side. Ensure you're using your obliques to do the work.
- Lower abs. Do leg lifts (hold weights in your feet, or lay on ball and do them). Leg raises (where you hang in the air and rotate your knees to your chest). Leg throwdowns (more advanced - lay down on a mat and hold on to something firm [behind your head]. Stick your legs straight up in the air [should be perpendicular to the floor]. Have a partner stand at your side and 'throw' your legs hard to the ground. Keep your back flat and use your abs to keep your feet from hitting the floor. Bring your legs back up and your partner throws them down again. Go until you can't do anymore). Get with a trainer at a gym to show you some new funky ab exercises
- Improve your nutrition to mostly eat low fat protein (chicken, fish, lean turkey, etc.) and veggies (i.e. broccoli). Mix a little fruit in there for some sweetness. You can also buy whey protein and make whey protein smoothies (2 scoops protein, ice, skim milk - blend - little peanut butter, ripe banana, more ice - blend again: tastes great). Cut out junk food (especially soda, anything loaded with high fructose corn syrup, all sweets, etc.)
- Start taking a thermogenic fat burner (will burn fat faster when your body temp rises - i.e. working out), ripped fuel, or hydroxycut hardcore before your workouts. This will help provide energy for workouts during your cutting 'diet'. These also help you burn fat and are 'good' supplements to use
Work hard...have fun

P.S. abs (stomach) is where I (along with many others) store most of my excess fat. It's the hardest part of my body to get to 'come in' (i.e. lean out) but you can see the results.