The type builder panel forms part of the Type Browser dialogue.  It presents a root type that must be resolved.  To achieve this, types are found and selected using the known type lists.  Sometimes a single type will be all that you require. However, more complex root types can be built and these are presented in the panel as a type node hierarchy, an example of which is shown above.  The description associated with each node will help you to understand what it is you are being asked to select.  Additionally, not all types will necessarily be eligible for selection for a given node.  So when you select a node, the types available for selection may be a subset of the known types.