How to add files to the VM

Step 1: create the disk image:

on the pi install brasero like this: sudo apt install brasero.
put all the files you want in a folder somewhere you remember like ~/Documents/myfolder.
open brasero and click on Data project
click on the plus sign in the top left corner.
select the folder/folders you want and click on 'Add'.
click on 'Burn' in the bottom right corner.
give the file a name, and then click on 'Create Image' in the bottom right corner.
wait untill you see a Image successfully created message like the one in the screenshot bellow:

open terminal and type: cd <VM> but change with the name of the vm's folder. look for the table bellow for a list of names.
type the command to start your VM (the commands are in the README) but add this to its end: -cdrom path/to/the/image/we/created/earlier.iso but of course change path/to/the/image/we/created/earlier.iso with the real path to your image.
Example: to start the MacOS 9 VM with a 'cd' called files.iso this is the command I would run:

 qemu-system-ppc -M mac99 -m 1000 -cpu "g4" -L pc-bios -g 1024x768x32 -hda ~/macos921/macos921.qcow2 -cdrom ~/Downloads/cd/files.iso

to boot from the 'cd' add this as well: -boot d.

DONE! when the VM boots up you should be able to copy the files from the image.

VM (OS name)	folder
MacOS 9.2.1	~/macos921
Windows 98	~/win98