an example for you:

on the back of a 1oz bag of peanuts:

Serving size 1 packet
calories 170
Total fat 15g
Saturated fat 2 g
Polyunsaturated fat 4.5g
Monounsaturated 7g
Cholesterol 0mg
Sodium 115mg
Potassium 190mg
Total Carbohydrate 5g
Dietary Fibre 2g
Sugars 1g
Protein 7g

you would take the carb count which in this case is 5 and subtract the dietary fibre count from the carbs which is 2...they amount of "net carbs" would be 3g.

you always subtract the dietary fibre fromt he carbs on the labels unless it says that they have already subtracted them, which I don't see very often.

I hope this helps!!