Weight loss is 80% diet, so your primary focus needs to be on finding an eating plan that you can stick with for the next 40 years. People who are significantly overweight are overeaters. Often these same people use food as a self-comforting medication. If you eat or binge when you are tired, stressed, sad, lonely, angry, etc. you are an emotional eater. To deal with that you need to address the cause and find more productive ways of coping.
Food: Eat fresh veggies, lean protein, and small amounts of good fats (avocado, coconut oil, nuts) at a calorie level that is appropriate for you. Start by eating 1,500 calories a day. Cut out fast food, junk food, sweets, and soft drinks. Cut back on bread, pasta, rice, cereal, potatoes, dairy products, and fruit.
Exercise: how many calories you burn depends on the speed and resistance you use on your bike. Start by spinning for 30 minutes a day with the goal of increasing your Rotations Per Minute (speed) and the resistance as well as the time. For example, when you can keep your RPMs to 70 or above, increase the resistance.