Sang Shin has included WidgetFX as part of his 15 week JavaFX Programming Course that is currently underway. This is a free online course that you can take at your own pace based on his excellent training materials.
The scheduled date for the WidgetFX module is July 25th, and will feature an online lab and homework to teach basic widget development.
Sign up at javapassion.com and sharpen your skills on JavaFX and WidgetFX for free!
While you are learning WidgetFX, this is a great opportunity to toss an entry into the Widget Developer Contest that is running until the end of July.