Calories are a unit of energy. To put it simply, calories tell you how much energy you get from a food source.
The more calories you eat, the more energy you are taking in. That energy has to go somewhere though: some will get used in digesting the food; some will get used by your body carrying out various functions and processes your body does to keep you alive and functioning; some will get used by the muscles to keep you doing whatever you're doing now, when you go to the gym later etc...; some will even get omitted from the body when you go to the toilet!?
Then if there's any energy left, it will get stored in your body... usually as body fat.
So do you need to be counting calories?
Maybe, maybe not?
For me, it's somewhere you can go, but it's not the place I'd start. I'd start off by working on food choices, going more for good sources of protein and loads of veggies with meals, the odd portion of fruit, then some fibrous and starchy carbs, mainly around training. Limit the amount of high calorie, sugary, fatty treats like cakes and chocolates and also limit alcohol intake. Once you're doing this and creating some good habits that allow you to sustain this way of eating, then you can start look at counting calories... only if you need to.
Losing weight and dropping body fat maybe a simple process in terms of using more calories than you're eating, however it's not an easy process. Also, one of the biggest struggles people have is being consistent and sticking to a diet... so why make it even harder by having to weigh everything you eat!?
Initially, keep things simple, work on food choices, build some positive habits, keep a food diary and training log, then if progress loss slows or you want to get really lean, then and only then should you start to count calories.
As I see it, there's more to life than worrying about every little thing you're eating and counting calories can help you to see where you might be going wrong, but it can also lead you to obsessing over what and how much you're eating and this can lead to a bad relationship with food.
For me, part of being healthy is being ok with eating a bit of junk occasionally, having the occasional drink in amongst mostly nutrient dense, whole foods. It's not about panicking every time you go near a biscuit!?
Hopefully this clears things up a little for you, however if you do have any questions, drop me an email to email@example.com and I'd be more than happy to answer it