Fitbit, My Fitness Pal. Link together, record your food. If there's a recipe they wouldn't have (mom's chicken soup, etc.) you can enter your recipe or just pick an entry that seems similar and log that. It will calculate your current weight, goal, calories eaten, calories burned (per fitbit--link to your fitbit account by following the prompts--easy even for me), and calories left to eat if you were to burn no more that day. This adjusts as you burn more calories/eat more food/sit on the couch... When the calories left get to zero, either stop eating or exercise more.
For most people, if you don't record your food, you will eat MUCH more than you realize. You will also eat foods that have way more calories than you thought. If you want to know about a food before eating it, just look it up but don't enter it unless you decide to eat it.
You will lose weight if you do this, no matter where the calories come from. If you'd rather get rid of fat and keep muscle, then exercise. Do a mix of aerobic (such as walking) + anaerobic (resistance such as weights or using your body as the weight). Also, keep the carbs focused on nutrient dense, low-glycemic-index whole foods and generally focus on protein above other nutrients--preferably meat, whole dairy & eggs. You can do this as a vegetarian/vegan, but you'll need to study how to do it properly or your health will suffer.