In order to figure out how many calories you should be eating a day, you need to have information on a number of factors. These factors are your age, height and weight. Once you figure out how many calories you should be eating a day, then you can start your weight loss plan.
That depends on your size and your activity level. The idea is to eat less calories than you are burning. Find your BMR and go from there. Here's how to find your BMR.
To lose weight the healthy way, eat at least 1050 calories per day and probably no more than 1500 calories per day (depending on how much weight you want to lose). For more information, visit diet plans for weight loss.