{ First we need to tell the Application object the name
 of the Help file and where to locate it. }

Application.HelpFile := ExtractFilePath(Application.ExeName) +
 'YourHelpFile.hlp';

{ To Show a help file's content tab: }
Application.HelpCommand(HELP_CONTENTS, 0);

{ To display a specific topic of your help file: }
Application.HelpJump('TApplication_HelpJump');