You cannot write Amiga floppies with PC without special hardware. The best solution would be to ask a friend with networked Amiga to write the floppies for you. If that is not possible, then the cheapest way is to use a nullmodem cable between your PC and Amiga. See
here for instructions and software for Amiga and PC. The only problem is that you need at least a working Workbench disk... Using a nullmodem cable is also quite slow. It takes about 8 minutes to transfer one image.
