im on a goal to reduce my body fat percentage. when i do cardio, should i concentrate more on losing more fat calories or calories?!?

Is there a way to tell the difference between fat calories and other ones as you work out? I have never heard of this.

I'm interested in knowing how to reduce body fat. I am about 21-22% body fat which is too high for my height and weight. I am 5'10", 130 lbs. Does anybody know how I can lower my body fat to about 15% without losing or gaining weight?

15% is really low, unless you’re a man. 15% body fat for a man is really good. So from your username I think you a woman, and 15% body fat isn't really a good goal, unless you want to be a body builder or something. 18% is probably a better goal. A female track runner has a body fat from 12-20%. And get your body fat check with a skid fold test, not on of those Bioelectrical Impedance Analysis things. they suck. Manly because the percent can change with in MINS. Say you take the test, then drink a liter of water in the next 10 min, and take the test again; you will probably get 2 different readings. So go to a fitness center in ask to have a skin fold test done.

there is a big difference between fat calories and general calories. When you exercise with an elevated heart rate, you are burning a lot of calories ... which includes fat and other types of calories, like protein. THis is not good if you are also trying to build some muscle definition. That's why, most exercise machines have a setting for "fat burning" ... which is not strenous exercise ... it's more like a light jog. However, you do not burn as many calories .. so there is a trade-off.
There is a compromise ... HIIT (High Intensity Interval Training). As the name implies you are doing intervals of high intensity ... ie. jog for 5 minutes, sprint for 1 ... or, what i like to do, jog for 45 sec, sprint for 15. This is supposed to be a good balance of burning a lot of fat calories without burning too much protein.