If you want to learn clothing CAD, you must first learn the process of hand-made clothing or the basis of hand-drawing. The more skilled the better. Clothing CAD is to design patterns with computers.
I just do garment CAD and make patterns. I operate ET (Buyi) clothing CAD software. I have a complete set of et (Buyi) CAD video tutorials. If you are interested, I can give them to you. I wish you success in your studies.