When a clean image is opened only two tools are open: the Launcher and a Workspace. The Launcher is the primary tool for opening additional tools, and also has a text area, called the transcript. The Workspace is a sandbox for testing code.
Most coding is done in the System Browser, which you open by selecting Browse | System in the Launcher. The System Browser provides access to all classes in the system, either by their containing package (or bundle or packages), or by class hierarchy. The package view is the more common working view.
Additional tools are opened as requested from the various menus in the Launcher and other tools. Online descriptions are available for most of these from the Help menu.