Just download a thing like my fitness pal and count calories. It's what I did and I dropped 20kg.
I also swapped out things like Coke for Coke Zero if I was needing a fizzy drink, sure it's not much "healthier" but less calories.
Skipped on having fries when it came to eating burgers etc.
I cut out beer, if I was needing a drink I'd drink straight spirits - less calories.
Stay below your "maintenance" level of calories per day and you'll lose weight, simple stuff. I didn't go completely healthy and eat a piece of lettuce for dinner, I still enjoyed junk food just had less of it.