1. Create a new diskimage in the screen with the diskmounting-options.
2. Mount this diskimage as diskdrive A:
3. Start the emulator and click on A:
4. Copy the file from harddisk to A:
What's your problem?
Anyway, I suggest you should use STEEM (steem.atari.org) or SAINT (saint.atari.org)
instead of (old and unstable) PACIFIST.