You are asking the question that has sparked a thousand wars around here! Simple answer: Only YOU can determine your caloric needs. The online calculators will give you a rough estimate, but it is ultimately your metabolism, energy expediture, and actual calorie intake that will determine your fat and fitness. We've discovered around here it is nearly impossible to figure calories with much accuracy, due to misleading labels, weights, etc... It is also impossible to figure energy expenditure.
The only way I have seen it work is for people to eat for nutrition and satiety and see where it takes you. If you are getting fatter--cut some calories out somewhere. If you are not gaining like you should, add some calories somewhere.
You will need to play around with carbs/fat/protein to see what's best for you. This can take years, but the fact that you are taking steps towards a healthier lifestyle is immense.
My best diet advice: Cut out all refined white sugar, grain, and industrial vegetable/seed oils. Eat nothing fried, even in butter or olive oil. Read and re-read Mark's 'Definitive Guides' found on the Start Here tab as well as his books.