Don't panic!! The first thing u need to do is throw out/give away all your unhealthy food and drinks, If there is no temptation at home u r more likely to succeed! Only buy healthy foods, fruit, veg, low fat dairy. Swap crisps for things like oat cakes. Eat a filling healthy breakfast like muesli, snack on fruit, buy wholegrain bread pasta and rice and drink lots of water. Use fry light to cook rater than oil. Have some sweet treats when u fancy but look at the calories before choosing!! Low cal jelly is great and low fat yogs eg muller light vanilla and choc. Make a plan of action and stick to it. Master healthy eating first then consider a diet if need be a but later but I'm sure u will see a huge difference if u try this for a few weeks. Good luck, u can do it!!!