Search for a TDEE calculator or use MyFitnessPal to calculate your calorie allowance based on a goal of 1lb loss per week.
I was 225lb when I started, height 5ft 8, age 40, activity: sedentary and my target was 1670 per day. I have lost 2 stone in 16 weeks sticking to that.
In terms of what to eat, carbs hold onto water, can affect sugar levels and are generally high calorie and only filling for a little while before leaving you hungry again. So I tend to reduce and think more carefully about those. For example I don't eat bread but do have ryvitas,
Proteins and fat will leave you feeling fuller for longer and are less likely to cause water retention, so I make up batches of things like chilli or bolognaise, go heavy on mushrooms, tomatoes, carrot, onions, peppers.... to bulk them out and have a portion of that for lunch. I use a 500g pack of 5% fat mince and that makes 4 good sized portions and if you use low calorie veg it's about 220cals per serving.
Breakfast I've always not been fussed about but if I do wake up hungry then I have scrambled eggs or 2 egg omelette and again add some veg like onion, chillies, peppers to make it more filling and hearty without adding much to the calorie count.