Codename One training is available for free when signing up for a pro/enterprise account. You can review the course and its material here.
Once you sign up for a pro/enterprise account you will receive a coupon that will allow you to signup to do the Udemy course for free.
The Codename One 101 course on Udemy includes ~45 videos with more than 18 lectures and over 20 exercises/their solutions. We also have a couple of other free courses on Udemy specifically:
Learn Mobile Programming By Example With Codename One and Build Mobile iOS Apps In Java Using Codename One.
We also have the completely free How Do I? section that includes short guides to help you out with common day to day tasks in Codename One.
You can get documentation, demos and other materials such as our developer guide, javadoc etc. in our developer section.