Regardless of what those pushing fad diets will tell you, models and celebrities don't look the way they because of diet alone. Their big secret--if there is one--is having personal trainers to develop a customized fitness plan, and to motivate them when they need it. Of course, not everybody can afford personal trainers, but a lot of gyms will have somebody on staff who can help you for free or a lower cost. At the very least they should be able to instruct you in the proper use of any equipment your using.
But, just as models and celebrities don't get in shape through diet alone, neither can you get in shape by just using a body building workout. In fact, it's a good idea to take a look at all of the elements of your current lifestyle. As long as you're trying to get fit, you may as well attack it from as many angles as you can. For example, if you drink too much or are a smoker, then it's time to kick those habits. It won't always be easy, but you'll feel great that you're improving your health in such a powerful way.
When it comes to a body building workout, you need to decide what your main goal is, as it will determine which exercises you will do most often. For the most part, if you are trying to build bigger muscles, then you need to lift more weight, but do fewer repetitions. On the other hand, if you want to be toned--to have more definition to your muscles without looking bulky--then doing a lot of repetitions, but with lighter weights is your best bet.
Healthy eating will help you see more impressive results from your workout efforts. The first thing you need to do is stop eating fast food. Next, try to eat foods that are as close to their natural state as possible; refined foods don't have enough nutritional value, and you need to take in calories that are high quality. Load up on as much whole grains, lean protein, healthy fats, and fresh fruits and vegetables as you like.
As you can see, a body building workout is about a lot more than just lifting a few weights. If you want to see real results, and stick to it, then you need to take a complete approach to improving your fitness. It may be challenging, but once you look the way you want, you'll be glad you stuck with it.