http://www.atkinscenter.com has the details about what carbs are useful / amounts to consume in each of the four phases of the Atkins nutritional approach (that's what Dr. Atkins preferred to call "the diet" so that people would understand it's a transformed way of eating rather than a short-term program).
Also, Dr. Atkins' New Diet Revolution explains what carbs / amounts of carbs per day are consumable while losing weight, and how many per day (and what kind) to use in each phase.
Personally, I have to stay under 20 grams of carbs a day (no pasta, potatoes, etc.) to lose weight. It's not difficult to do because it doesn't take a lot of food to fill me up when I eat what my body needs to keep my blood sugar under control (hypoglycemia).