30 minutes of intensive cardio a day minimum, preferably an hour. Do weights also. For now set your calorie intake per day to 2000 tops spreading out over 4 or more meals.
You're very big, but because of that you can see results on the scale very quickly. I assure you that if you started doing 30-60 min of cardio a day (it would unfortunately be slow at the beginning since you're not fit yet) and jacked your calories down big time (count them) a week from now you'd be quite surprised at how much fat you have lost.