The first of the buttons on the Explorer Panel Embedded Toolbar is the Toggle Folder Tree command, This button will show/hide the Folder Tree.
The Folder Tree can be scrolled independently of the Explorer Panel, and clicking on any node of the Folder Tree will change the Explorer Panel to display that subfolder. The nodes of the Tree are shown with "+" or "-" symbols to show whether the subtree is expanded or collapsed.
You can also drop files on a folder in the Folder Tree and then a copy operation will begin. The copy operation will use the folder on to which the file was dropped as the suggested target folder.
Pressing the refresh shortcut command (F2/F5 depending on setup) while a folder in the Folder Tree is in focus will refresh that Tree node .