The projects, folders and files that you create with the Workbench are all stored under a single directory that represents your workspace. The location of the workspace was set in the dialog that first opens when you start the Workbench.
If you have forgotten where that location is, you can find it by selecting File > Switch Workspace.... The workspace directory will be displayed in the dialog that appears. IMPORTANT: After recording this location, hit Cancel to close the dialog, or the Workbench will exit and re-open on whatever workspace was selected.
All of the projects, folders and files that you create with the Workbench are stored as normal directories and files on the machine. This allows the use of other tools when working with the files. Those tools can be completely oblivious to the Workbench. A later section will look at how to work with external editors that are not integrated into the Workbench.