There are several guides in the WildFly 9 documentation series. This list gives an overview of each of the guides:

*Getting Started Guide - Explains how to download and start WildFly 9.
*Getting Started Developing Applications Guide - Talks you through developing your first applications on WildFly 9, and introduces you to JBoss Tools and how to deploy your applications.
*JavaEE 6 Tutorial - A Java EE 6 Tutorial.
*Admin Guide - Tells you how to configure and manage your WildFly 9 instances.
*Developer Guide - Contains concepts that you need to be aware of when developing applications for WildFly 9. Classloading is explained in depth.
*High Availability Guide - Reference guide for how to set up clustered WildFly 9 instances.
*Extending WildFly - A guide to adding new functionality to WildFly 9.