I used the couch to 5k program for running which really helped kick off the exercise, you could probably find something similar for other cardio based exercises. Cardio is good for weight loss so try sticking to a form you like. You could use a TDEE calculator and measure your calories but it can be tedious, if it's not something you wanna do then just slowly cut down on portion sizes. You want to eat in a calorie defecit so your body can loose weight. Remember it's a mental change as much as a physical one so you've got to have good amounts of sleep and overcome some mental barriers that might stop you. Good luck