After did some researches and discussions with some trainers this is what I come out with: The appropriate exercise for obese should be minimizing the joint stress and remember to start slowly. As you get stronger, you can gradually increase your time and effort.
The simplest thing to do is walking. Try to walk with short distance and short period of time. Do not force yourself if you cant do it. Week by week add a little bit of your distance and time. It takes lot of patience whilst you want to lose weight RIGHT NOW. But hey, you are making new habit not a quick fix. You will see the result stick much longer if you train and eat sensibly than people who overtrain and go with fad diet. Believe me ladies...been there done that!
Another exercise you can do is swimming. Swimming is very excellent way to burn calories without stressing your joints. The water supports your weight and minimize the impact.
If you are a member of a gym, please avoid cross trainer machine because it involves twisting, no rowing or stepper machine. Do more floor based exercises to strenghtened your core,muscles and glutes.
Obese people have lot pressure on their heart, therefore watch closely to heart rate since exercise could be detrimental for their health.