Suppose you are working with the Mammals example document. Its case table looks like this:
You want to the maximum Height as a summary statistic.
Click on the plus in the table (circled in red above).
Define a new attribute as shown here:
Drag the new attribute all the way to the left into the empty space to the left of the Mammal column.
The result is the beginnings of a summary table.
Repeat for each summary statistic you want to include.
And if you want to break the summaries down by a grouping, Diet for example, drag that attribute over into the same part of the table.