I think there are two strands to carb counting:
1. Literally counting the carbs - the act of carb counting
So... How to work out how many grams of carbs the food you are eating contains. Things like carbs and cals, cook and count, myfitnesspal and nutritional labels are useful here. Along with weighing scales/measures.
Probably little need to do a course to work out how to do the counting of the carbs itself.
2. What to do with the information on how many grams of carbs you are taking in - the diabetic management technique "carb counting"
Using the information on how many carbs you are taking in to figure out your insulin to carb ratio, check that the ratio you are using remains appropriate for you and/or make adjustments.
So this is where it gets more interesting/tricky and a course is actually really helpful!
This is what the Bertie online course deals with, along with basal adjustments, and tips in dealing with exercise and sick days.
Other resources useful for the diabetic management technique "carb counting" would include the book think like a pancreas. I'm trying to think of more, but Bertie online is probably the best place!