you use backup-creator with the common-key and iso in the same directory.
So say i make the directory c:\BackupCreator
Put backup-creator.exe, common-key and game.iso in that directory. (game.iso being whatever game you have)
Then in dos or other command shell go into the C:\BackupCreator directory.
at the command prompt type:
backup-creator.exe game.iso
It will create the file "partition.iso" in the same directory
takes a few minutes to create the file. wait for it.....
then burn the partition.iso with imgburn.
there is also a gui for it called WiiISOPatcherGUI.exe that makes things easier.