Hi there and congratulations on taking the first step towards better health.
Before you start on this journey you should try and get your mind ready. Firstly, consider this a lifestyle change, rather than a "diet". Diets are temporary, and will fail in the long run unless you can wrap your brain around the idea that you are making permanent changes.
Next you should do a little research on the foods you will be eating and how they affect your body, moods, mental state, etc. And take a look at what your current diet is doing to you. I find that being aware of what that can of soda pop is doing to me helps me avoid them - even though I LOVE coca cola.
Meal planning is extremely helpful. You know what you will be eating during the day, so it helps you to not reach out for those "no no" foods.
Some of the rules that I follow are:
No "white" foods. Like white flour, white rice, white pasta, white bread, white sugar and potatoes.
Instead it is whole grain variations...whole wheat pasta, brown rice, whole grain cereal, etc. And these should be eaten in measured amounts.
You can have up to 6 eggs a week, and as many egg whites as you wish. I have a whole grain english muffin with an egg for breakfast fairly often.
Try and keep red meat down to once, maybe twice a week. Instead use chicken, turkey or fish.
Eat vegetables (except potatoes). Salads, stir fries, soups, veggie plates...raw or cooked. This has to be the main focus of your diet. As many different kinds as you can eat, the more brightly coloured they are the more nutrients they have.
Fresh fruit is a good choice too, instead of sweets.
Try and drink 6 to 8 glasses of water.
If it seems overwhelming, start slowly, making one change at a time.