The Editor Window can be found at: Window--> Editor and allows editing of several types of NICE files:
Any file being edited will appear in its own tab with its own type of editor. Regardless of where the client is being run, save/load actions access files on the NICE instrument server, unless you specifically choose to load/save on your local client machine. You will typically want to save in your own experiment folder, or the common folder (admin-only).