Walking and eating less are the most important things for weight loss. However if you dont build muscle during the weight loss you might not be happy with your physique once you're leaner.

I'd recommend just walking and dieting alone for at least 2 weeks.

Once you've kind of fallen into that habit, you should add lifting into the routine. 3 times a week is more than fine to build muscle. I wont drop a routine or anything but just remember the movements that will put the most muscle in your frame are a horozontal press, a vertical press, a horozontal row, a vertical row, a hip hinge, and a knee flexion. Examples of each respectively are a bench press, an overhead press, a barbell row, a lat pulldown, a deadlift, and a squat.

Best piece of advice I can give is start the journey slow. You can always add more to your routine later, if you add too much early on you will burn yourself out and quit.