It's just a command-line based program. You have to start it from the Shell and specify which file you want to write to disk, and the drive (although that defaults to df0:).
So let's say you have an image called Assasins1.adf on your hard drive. Then...
devcopy dh0:Assasins1.adf
...would write the Assasins1.adf file from the hard drive to df0:
If you want to copy the image to a disk in df1: then
devcopy dh0:Assasins1.adf unit 1
would do the trick!
