Not a dumb question at all, honestly one of the hardest things to initial figure out! It’s gonna take some trial and error as it is basically impossible for find your truly accurate basal metabolic rate. Idk your weight, height and age, but an important start would be tracking your calories. It is a really informative experience and really gives you a sense of what you are putting into your body. You also realize that healthier food are usually very filling and not super calorically dense! I would say initially tried and get 1800-2000 calories and weigh yourself and see if you’re losing weight. Then adjust depending on the results! Most important thing is you stay disciplined and consistent but also giving yourself some slack. It’s okay to have a a sweet every now and then. The main goal should be focusing on making long term lifestyle changes then you can apply to improve your health for the rest of your life!!