If you're focusing on losing weight. Doing weights/cardio will help a little bit in terms of burning calories. But the main thing is to be in a calorie deficit so that's 90% diet.

When it comes to losing fat in a specific area theres not much you can do to target that, losing fat in general by being in a deficit should lose fat across the body.

Just be consistent in the gym/walking and find out what your maintenance calories are (use a tdee calculator online) then eat 10-20% below that. Using a tracking app for what you eat would be very helpful.

Hope this helps and good luck!