I don't want to assume that you made the mistake, but the Smoz tool is interesting in that you don't actually "open" the program.
Best option is to put a copy of the rom in the same folder as the tool, and drag it onto the Smoz tool in the same folder.
the Smoz tool will then open itself up and start asking you what options to want to add/drop from the rom.
Cheers,
Jer