Open source
SuperFields are open source (released under Apache 2 license). The repository page is the main source of knowledge, including wiki on how to use certain features.
Relevant links
Online demo
The most recent release for the latest supported version of Vaadin has an online demo. The source code for the demo is available in the repository and you can run it locally, too.
Vaadin Directory
SuperFields are released on Vaadin Directory - the add-on page additionally serves as a place for discussions. In addition, SuperFields are available from Maven Central.