First thing you do is clean up your diet, eliminate any unnecessary junk. Then start lifting weights to build muscle in your legs and cardio to lose any extra body fat you want to get rid of. You can do workouts like hill sprints which will build muscle and burn fat and I think plyo too, because you jump a lot with plyometrics.
You can do ab exercises to tighten and flatten your abs, but those alone won’t flatten your stomach if you have fat that’s hiding your progress!
I’m not an expert at losing weight though so I can’t really give you a detailed response but I’m pretty sure that’s the basics :)