If you are tryin to get into shape, the first thing you should do is set some goals. How much weight would you like to lose? How much muscle would you like to gain? How fast do you want to run the 40 in? Be realistic. You should also decide how much time you can dedicate to exercise.
Secondly, you need to come up with a routine. Like FILAlAUS said, consistency is the key. I usually rotate between two routines:
One muscle each day (chest, legs, back, arms, shoulders) OR
Two muscles each day (Chest/tris, Back/bis, legs, Shoulders/chest, Bis/Tris etc)
You should also work your abs at least every other day, and cardio almost every day. When you do your cardio, dont do that shit half assed. Run, jump rope, use a stair master, do shit that will really make you sweat. You can also hit a heavy bag and get a real good workout, I do it AFTER lifting because it makes you so tired.
Eat according to your goals. If you work out a lot and you dont want to lose a lot of weight you can eat like shit. But if your asking for advice on the siccness (no offense) Im sure you are pretty out of shape. DONT use hydroxycut, a protein diet, or any other scam you hear about. EAT HEALTHY. Eat your fruits and vegtables. Eat lots of meat, steak, chicken, turkey, tuna is great, etc etc. Protein shakes are great too. It is also important when you have your protein. Have some around 1hr before and about 30 min after you work out. DONT drink things loaded with calories: soda, juice drinks (from concentrate almost all sugar), chocolate milk etc.
Keep in mind, this will take time. It does not happen overnight. If you have discipline, and faith in yourself, you will fight the good fight and meet your goal. If not, you will spend shitloads of money on good foods and now exercise toys and fail.
Also, if you have never lifted weights before contact a trainer and learn the machines and right form. It will be worth the one lesson.