File >> New >> Empty OOB : allows you to create new empty oob. The oob file will be created or overwrited. Basic structures will be put to the file (Armies and General Supply). Each army will have a leader.
File >> New >> Attached OOB : allows you to create new oob, basing on an attached one. The oob file will be created or overwrited. It will be filled with data coming from the attached file. Warning! The attached file should not be modified. After setting all workspace properties you will see a following dialog box:

It will contain all attached oob's. Select one of them and press Accept to proceed.
File >> New >> Existing OOB : allows you to edit an existing oob file. The file will not be created or copied, instead it will be opened for editing.
File >> Load : use this command to load an existing workspace & oob file.
File >> Save : use this command to save the current workspace & oob file.
File >> Save as… : use this command to save the workspace file under a new name (the old file will not be removed). The Save as… option does not affect the oob file. To change this, you must use Workspace Properties dialog.
File >> Properties : use this command to open Workspace Properties dialog.
File >> Exit : use this command to exit the program. You will be asked to save the oob file, if it will be unsaved.