Press F5 to run the project, and you will see the outline in action. If you click on one of the nodes, it will expand or collapse to show or hide the data under it.
You may also press SHIFT and click on a node to expand the entire outline to the node's level, or press SHIFT-CTRL and click on a node to collapse the entire outline to that level. For example, if you press SHIFT and click on a file name, you will see all file names and all sections, but no token data. If you press SHIFT-CTRL and click on a file name, you will see all file names, and nothing else.