Read a book and skip the course, this skill is something best learned by doing and repetition.
For that join a race crew. There pay attention, ask questions, and solicit the foredeck ape to mentor you. A dozen days where the
spinnaker goes up and down several times a day, and you'll get it down. Look for a boat with the
spinnaker setuppyou want to understand best - such as "symmetic
spinnaker with dip pole gybes", or sail on different type boats and learn 'em all.
Good luck.