This is the central hub for all documentation regarding the Integrity Test Framework. Since the project is still rather new, it is plagued by the usual problem: the documentation still has to catch up quite a bit to the functionality already provided by the framework ;-)
Use the navigation on the left side to view the various tutorials and advanced topics docs already available. The tutorials cover quite a bit of the most basic functionality, so that is always a good place to start. I'd love to extend them to cover all the advanced stuff (of which there is a lot!), but unfortunately I don't know when I'll have time to do so :-(.
In addition to this, there is of course the Javadoc reference of the entire Integrity framework. Especially all the special-purpose fixture interfaces are quite well-documented via Javadoc; the more internal stuff of Integrity does have at least basic Javadoc coverage as well.