CompuServe Messages

Help.. I guess I missed something awhile back. ? How do you get a file with ".EXE " to run. I spent awhile and a few $$ downloadning some postscript files. When I tried to decompress them with the LHA programs I have, A message came up for me to get a newer version. So I went back on to download LHA213.EXE form one of the libraries. However, I cant figure out how to get this "SELF EXTRACTING" file to extract itself. Could someone guide me. Like I said, I must have missed something along the way. I am using an AMIGA 3000 with 2.05 DOS. THanks – Lowell