Listen to Joe. Believe me his advice helped me lose a ton of weight.
Now the 3,500 calorie = pound sounds right when you first think about it, but here is the thing. Your body burns a certain amount of calories per day on its own. For the most part this is around 2,000-2,800. Lets say you start eating only 1,500 calories a day. For about the first week or two you probably will drop some weight very fast, but then your body realizes its not getting the calories it needs, so it goes into starvation mode. This is when your body will start storing more calories than it should. = more body fat being stored instead of burned.
My best advice is going to be like Joe said, You gotta get up and move. If you cant run than atleast do a fast walk.
I started at 270 pounds back in Feb. I did my diet so it was 1,500 calories 1 day, 2,000 the next. And just repeated that. But you need to make sure its good and healthy food that you are eating. 1,500 calories of candy bars is like asking for a heartattack.
I started my exercise routine by simply walking. I walked 4 miles a day for about 4 weeks. After that I went to 2x 4 mile walks a day for 2 weeks. Then to a 4mile walk and a jog for as long as i could manage for about a month. After that first 2 and a half months i was able to jog a mile at a time pretty well. So I started jogging 1 mile twice a day along with my 4 mile walk.
I was 6'1 270 at the start of feb. and as of the end of may I was down to 220. I now maintain a weight off 220-230 easily. I still run about 4 miles a week, and still watch what i eat, but now my diet is more free up to eat the foods i love.
I wish you the best of luck on your goal and do know that it is possible to get this down without killing yourself. Hardwork and determination and next thing you know you will be checking yourself out in the mirror everytime you walk by one.