If you've never tried dieting, counting calories or carbs, etc, you might want to check with your doctor or have her/him refer you to a nutritionist or dietician, who can make sure you get the nutrients you need and can also explain what constitutes carbs, proteins, fats and other nutrients.
You will also need to start an exercise program that's appropriate. Start slowly, by taking a brisk walk for 30 minutes daily, then increase as you can. If you over work and your muscles get sore, you may not stick with it.
I also have a lot of weight to lose and I have recently joined Weight Watchers. I have had success in the past with it. I just have to stick to it....that is my problem, I get bored with it. Good luck on your journey!
Denise