The File Format Associations dialog is used to register with Windows the file extensions that you want to be associated with TrueMap.  Check the checkbox next to all of the file extensions that you want to be associated with TrueMap.  The extensions that you select will be displayed in the Windows Explorer program with the TrueMap icon.  Double-clicking a file that has its extension associated with TrueMap will automatically start the TrueMap program and load the file.