How do calories work?

Ok so this is going to sound like a really stupid ? But I dont get like how calories work. how do you lose weight bast on calories and how much of them you eat and burn off??

Okay, calories are how much energy a specific food gives you. How many calories you need all depend on what you do during the day. But, if say, you normally eat around 1500 calories, but don't lose or gain weight, that is the same amount of calories that your body burns. If your body burns 1500 calories and you start to consume 1300 calories a day, you will lose weight, as your body must now burn stored fat to get those extra 200 calories. The reverse is also true. If you eat 1700 and your body only burns 1500, you will end up storing the extra calories.
One more thing; there are 3500 calories in a pound of fat.
Pls. don't insult yourself. There are, I my opinion, no stupid questions. If you are asking its because you want to know.