There is always a tutorial on how to use CAD but you need to know what you are using first. If you want something basic and free, Inkscape. If you have money there are much better things to use. If you put in enough time and effort into something it can be done. You may just need a direction to look. And being completely honest with you you may not need CAD to build an airframe all you need is something to go off of. Like a picture on paper to scale up or a full size 3 view. But more information would be helpful in assisting you
Like Dinos said, you might not even need CAD. If you do though, then first pick out a CAD that you want and search YouTube for tutorials. I personally use doublecad and I know of a good tutorial that has enough to get you started. Then there are things like Inkscape, freecad, autocad, and probably lots more. They probably all have tutorials too.
Well then sir, in my humble opinion, you have some of the best of CAD software! I know that there is a master series design help thread on the forums that may assist you. This is now out of my expertise so good luck!