Reset the View buttons and Tree selections to those shown below.
The View shows just two columns: Main Group and COUNT(Title). There are other columns but they are hidden. Currently the Tree is showing all the unique items from the Main Group fields. To show the next level of classification click the + box next to Fiction. The View now shows an additional column containing all unique items from the Main Classifications fields. These sub-groups are nested into their respective parent groups.
Note that the new column contains not only the unclassified sub-group but others from the Nonfiction group, even though they are not displayed in the Tree. The reason being that the Tree, as mentioned earlier, is intended primarily for navigation and so shows a condensed version of what is in the View.
Each time a sub-group is opened, the depth of the tree increases. At the moment the tree has a depth of 2. This is reflected in the View, which shows the first two classification groups.
Open the unclassified group. The View now shows a third category: Recommended Price. It may be that Recommended Price is not a very useful category on which to group our data, so extend the depth of the Tree by opening up one of the prices; say, 6.99.
We can now see a fourth category: Author. This is more useful, so we will upgrade it: click-and-drag the Author heading to the left, so that it swaps places with Recommended Price.
The Tree has now been re-drawn and collapsed to a depth of 1; the reason for this will be explained later. If you now expand the Tree again to a depth of 3 you will see that the third category is now based on Authors.
At this point you can save the current view and give it a meaningful name. Click the Save button at the bottom of the Tree panel.