If this is a game you downloaded you'll have to ask at the site you got it from.
Quite possibly true. He doesn't even bother to explain his DOSbox settings or image mountings or anything. I would assume the download file has images of the game floppies. Pretty sure you can't install the game in DOSBox unless you extracted the files from the disk images first.
Upon doing some digging, Fox Ranger is a Korean R-Type clone.
http://www.mobygames.com/game/dos/fox-ranger
EDIT: I see what his problem is now. WinImage can't open the disk images, so I have no clue what format they're supposed to be in (unless the FAT is missing something that WinImage needs).
You could mount the images as a virtual floppy with the appropriate software, then MOUNT them in DOSbox as Drive A and run the install program, but I don't see how this is possible if they're apparently unreadable.