Counting carbs is actually pretty easy to do. All you need is a source of information that gives the carb counts in grams of specific portions of foods. It can be a book, or a database or website on the internet..
I can recommend the following since I have them in my own library or use them frequently:
The most important part of counting carbs is to understand the difference between total carbohydrate measures, and the measure of usable, impact, effective or "net" carb carbs.
To count carbs accurately, use the net or usable carb number when adding up your carb intake.
If you are eating a ketogenic diet for weight loss, and you are new to counting carbs, I recommend that you keep track of what you are eating in order to be to count carbs accurately. This means keeping a food journal or buying software to track your food intake. After you've been on the diet for a while, you'll get a pretty good idea of how much carb is in different foods, and then you should be able to track it accurately without writing everything down.
Of course, if you are just eating a ketogenic diet for health reasons, you don't need to know how much carb is in your food. Just the act of cutting out the obvious carbohydrates (breads, crackers, pasta and sugar) from your diet will help you feel 100% better.
One note to remember: Some people on ketogenic diets use sugar alcohols to sweeten yogurt or low carb cheesecakes. Sugar alcohols are are sugar molecules which have been designed to be undigestible. (Examples include erythritol, mannitol, sorbitol and the like.) Many people in the low carb world feel that sugar alcohol carbs do have an impact on ketosis and blood sugar, and so they count them in when totaling up usable carbs. Other people are able to eat them without any effect on weight loss or ketosis. You'll have to learn what works for you by trial and error.
Carb Counting Books