Jamie lyn4, welcome to the forum, congrats on making this first BIG step...good for you, and also congrats on walking, it is a wonderful activity and as you get fit you will enjoy it even more. As for the 20NC a day, you probably would be good to start on the 40 NC plan, just saying, 20NC would suit someone that did not have a considerable amount to lose. You do not want to be hungry, and bored, you need lots of choices, you can tweek the plan as you approach goal, but for now, take this one day at a time, it is a learning experience and not a race. We have all been there done that...we are here to support and cheer you on.
I suggest that you keep track of EVERYTHING that you eat, there is a place here on this forum called MY PLAN where you can record your food intake, and also carbs and fat & protein. I use the Meal Tracker on the Atkins website, it is user friendly and I need all the help I can get, I'm a computer idiot...lol
And a lot of us have our own journals, it is a safe place to write down feelings, vent, complain, celebrate, and get to know other members, I encourage you to start your own. Looking forward to getting to know you, best of luck to you,

Have a positive day, stop by my Journal sometime, I love company, ttys