This guy goes through the basics of building a BLDC motor without getting too technical, he highlights the major considerations for his build:
http://www.instructables.com/id/Make-Your-Own-Miniature-Electric-Hub-Motor/step1/The-Brushless-DC-Motor/
http://www.instructables.com/id/Make-Your-Own-Miniature-Electric-Hub-Motor/step1/The-Brushless-DC-Motor/