I downloaded the hero editor some time ago. It didn't work except the first time. I always got the message "Head of the file is is wrong..., should start with 55AA55AA", something like that. File created by the hero editor was not recognized by diablo program.
After I read zonefire's comment on "changing language setup in Windows control box related to unicode", I changed my computer to support only English, then the hero editor works great. (my computer was setup to support non-unicode languages before)'

Thanks Zonefire!