Good luck to you bro, I used to be big before I finally got my ass into shape.
Cardio is how you lose weight. A big misconception is sit-ups and lifting weights will get you skinny, that is only part of it. (small part)
Doing sit ups will build muscle under your stomach and can actually make you look "bigger".
My recommendations :
Cardio: Every other day, 1 hour. (this can be basketball, running, jogging, biking, rollerblading)
Eat earlier in the day, not later. You can get away with eating higher calorie meals early in the day since you burn those calories throughout the day.
Eat 5 meals rather than 3. Try to break it up from 3 large meals to 5 smaller meals, your body processes everything easier.
I wouldn't recommend doing sit up and all that until you get closer to your target weight. You can aggravate lower back pain ( i am not a fan of sit up's) they are one of the most useless ab excercises.
My favorite healthy meal is chicken breast + brown rice.
I am just trying to throw some info out there for ya. I remember when I started getting heathy I was doing exercises and routines that didn't help out much.
My friend is a personal trainer so he gave me some good tips, hopefully they help you too bro.
good luck!