紧急求助

教程叫我编辑"autoexec.bat，把autoexec.bat中的"EXT:"字段编辑成如下的样子：
:EXT
%RAMD%:\extract /y /e /l %RAMD%: ebd.cab > NUL
echo The diagnostic tools were successfully loaded to drive %RAMD%.
echo.
LH %ramd%:\MSCDEX.EXE /D:mscd001 /L:%CDROM%
echo.
cls
echo Now installing Windows 98 SE
echo.
echo Loading...
path=%RAMD%:\;a:\;%CDROM%:\SETUP\WIN98SE\WIN98\
OEMSETUP.EXE
echo.
GOTO QUIT

但我左我原来的autoexec.bat里面根本找不到"EXT:"字段，那我怎样修改啊？？