Apologies J_T, I was merely trying to reassure you that both methods give the correct result for problems of heading and groundspeed.
It is very hard to teach CRP-5 in text, I would always recommend you get someone to teach face to face, and check what you are doing. If your own instructor is unable and unwilling, and none of your other club instructors will help, then you might do better at another club! It is part of an instructor's job to teach these things, and it is important, especially if you plan ever to become a commercial pilot, that you can use this instrument quickly and accurately.