Get an app, like MyFitnessPal and log what you would normally eat. Look at the composition of different meals as you are logging them. Once everything is logged look at the macros. If there is too much of something, think about which foods are causing it. You will have to scale down on those. If something is missing, for most people that would be protein, research high protein foods and work them into your meals. This process will make you realize that done foods are expensive (a lot of calories for not much nutrition) and you are better off completely removing them. You will likely also need to introduce some new food but generally try to stay as close to what you eat normally as possible, as this will make your diet more sustainable than if you just adopt a meal plan someone gives you.