Hope this helps even though im no expert.
the 3 main areas you need to focus on are
Set yourself goals try and be specific and to the point. you stated certain activities you want to get back into it, you wanted to loose bodyfat, how much, maybe have a number in mind and slowly work towards that.
look towards the after picture of yourself, take a before pic, then every 4-6 weeks take another pic so you can see the improvements you make.
the key is to have a balance of protein, carb and fats in your diet.
spread your meals out every 3 hours
For protein go with eggs, chicken, fish, whey protein, lean beef, greek yoghurt
for carbs go with oats, sweet potatoes, brown rice, quinoa
for fats go with nuts, avocado, salmon
add in veggies like green beans, peppers, broccoli, spinach
add in fruits such as blueberries, bananas, apples
if you can get a bench that's great the list of dumbbell exercises are endless
look online for exercises to target certain muscle groups
maybe split your muscle groups up on different days or do a full body workout 2-3 times a week. there both good choices my preference a full body workout gives you more of a cardiovascular workout so you burn more calories.
just remember the results will show you how much effort you really put in
hope this helps