Our material around custom reports today is only reference material. As mentioned in other posts, we do not yet have guides or training classes to support custom reports training, although it is something that there seems to be a lot of interest in so we are looking at that closely. I would look around on this forum for lots of great information about building custom reports.
To answer your question about. “Creation Methods” are for creating “objects” in relevance. For instance, if you go to your Web Reports QNA:
In the BES Session Inspector guide that you reference above, each object has “Properties”. For instance, if you look on page 24, you will see that the “bes action” object has dozens of properties… for instance, the first one is: