Unfortunately, i will need to install Windows on my machine.
How can i partition my second Disk, to get 200GB from it, creating a new partition, to install it?
Also, after installation, Windows will appear on Garuda's grub?
Emulating could also work, but i tried to create a machine on Virtual Box, using a ISO i have, but it doesnt identify the iso as a OS.
I also have a external HD i can use to install it, would be a good idea? Which format would i have to format it, so i could install Windows on it?
Please read wiki "Reporting bugs" and "Install instruction"
No picture for help request.
Dual boot is not supported by Garuda, sorry.
Use also arch wiki.
We cant give step by step lesson, again sorry.
Installing Windows after Linux is generally a recipe for a lot of problems. Your Linux install will usually be broken by Windows at some point.
Garada does not offer support in this regard. Generally people involved with the Garuda project do not run Windows, so we aren't going to advise on this subject.
If someone wants to offer you advice then be thankful, just don't expect dual boot issues will be supported here. Maybe some kind soul will offer you some advice.