You will find carbs and fiber grams listed on most food packaging... Subtract the fiber from the carbs and that will be your net carbs - the ones you must keep track of during this WOE (way of eating)...

If something has no fiber, than you just record the carbs...

This is copy from Atkins' website...

We have created the Atkins Net Carbs Seal to list the number of carbs controlled carbers need to count. We’ve subtracted all carbohydrates such as fiber, glycerine and sugar alcohols, which either are not digested or are digested but do not impact blood sugar more than negligibly. While we list the percentage and number of grams of total carbohydrates on the Nutritional Facts Panel on the back of the label, the number of grams after subtracting fiber and sugar alcohols with a negligible impact on blood sugar appears in the circle, the Atkins Net Carbs Seal, on the front of the package.

Hope this helps!

Jodi