As we all know nutrition is extremely important to good performance when you run (or participate in any exercise), however in the early stages of running you should not be looking to massively overhaul your diet. You will see benefits from starting to run and it is important to know that even if you eat exactly the same foods and quantities as before you will both lose weight and become healthy as a result of your exercise.
That said when you do come to address your food take it is important to make the right choices. It is important to still have your occasional indulgences if you want them and keep a healthy approach to food. So the right foods: plenty of carbohydrates to provide you with the energy, and plenty of protein which will help build your muscles to keep improving.
Carbohydrates
In terms of a weekly plan, look at the times of the day when you are running and work around them for your food intake. First of all, breakfast. If you run early in the morning, either because it is quiet or because it is the most convenient time in your working day, take some liquids and a banana or small bowl of cereal around 30 minutes before setting off because the energy afforded by this light meal will make the session more effective. When you return, remember to replenish your carbohydrates stock, sometimes with some bread or toast before starting your daily routine. If you are not running early then a nice simple breakfast of toast, bagels, cereal and a piece of fruit will be a great start.
At lunch again you are looking for healthy foods, the more you can make in advance and not buy in the better. Homemade food is generally healthy and does not have any additives and therefore is better for you, add in to the bargain its usually cheaper and making your own food is a win-win situation! At lunch time have some carbohydrates (rice, pasta, bread, potatoes) and a little protein (meat, beans, fish) for your meal. Add in a piece of fruit and your good to go.
Hydration is also very important so make sure to drink plenty of water throughout the day. It will be hard to drink lots if you're not used to it but regularly drinking water will give you a ton of health benefits and keep your body in best condition for running and life in general.
Evening Meal
If you go for a run in the evening it is important you have a good source of carbohydrates to get you through the run so again 30 minutes before try to have some toast or cereal and a banana to ensure you have plenty of energy on your run .
After that you are again looking at a self prepared evening meal, some protein, some carbs and plenty of vegetables in this meal. Do not worry too much about the time of night you eat your food as most of the research on this suggests it makes no difference to you when at night you eat, just eat at the time that suits you best. Again make sure you have plenty of water.
Finally snacking. It's not bad to snack, in fact very few things about food are actually ever "bad" for you. It is as always most important that you take on the right kind of snacks, fruit and veg are great, oatcakes, nuts, if you want protein then oily fish is great and an easy way to have a quick healthy snack. Enjoy your food, eat good healthy choices and try to stay away from processed foods and you will be on the right track.