I answered this for you in a PM, but lets talk about it here too. Xenadrine is one in a long list of thermogenic fat burning supplements that are on the market today. They will help to speed the metabolism, give you some energy, and supress the appetite....BUT WILL NOT PERFORM MIRACLES! Cardio/training/and diet are what produces the real results...Xenadrine will aid in this process only if all of the above are in place.
Now, you are also a young guy. I usually do not like to recommend these products to anyone under the age of 18. There can be side effects, and health risks, if you have a heart condition, high blood pressure, a high sensitivity to stimulants, AND if you use too much or use it too often.
At your age your metabolism should be fast enough to get you ripped. But if you use a fat burner, PLEASE don't use more than the label recommends...in fact, use less, to see how you react to it first!