I used MyFitnessPal to log my calorie intake (and I love it!)
But as far as figuring out your daily calorie intake, you need to use a calculator to figure out your BMR (basal metabolic rate) - and add your activity level to that. MyFitnessPal does do this for you but for some reason, it never has given me accurate results.
I have used WebMD's metabolism calculator (found
here) in the past. Also, I have a BodyMedia Fit so I know pretty much exactly what I am burning every day from what my armband says. The WebMD calculator says I burn almost exactly what my armband says every day (an average day, at least - sometimes I burn more, but never less than what the WebMD calculator says).
So after you figure out your daily calorie burn, you need to figure out how much you should eat every day to lose weight. Let's say, for example, the calculator says you burn 2500 calories every day. Let's consider that it takes a 3500 calorie deficit to lose one pound. So, to lose one pound per week, you need to have a 3500 calorie deficit throughout the week. To lose two pounds, you'd need 7000 calorie deficit. If you burn 2500 calories on the average day, you'd need to intake 1500 calories to lose (roughly) 2 pounds per week.
(2500 daily calorie burn - 1500 daily calorie intake = 1000 daily calorie deficit)
(1000 calorie deficit * 7 days in a week = 7000) 7000 calorie deficit.
(7000 deficit / 3500 calories that it takes to lose a pound = 2)
This equation would mean you'd lose roughly 2 pounds per week.
I would recommend using the calculator to find your metabolic rate and then go from there to see how much you need to intake to lose x-amount of weight per week. I hope that helps!