How can I boot Windows on my PC?

I have a PC that was running Windows 7 at the time. At some point back then I installed Linux on this PC, which was supposed to serve as a server.

When I start the PC with the hard drive, I can choose whether to start Linux Mint or Windows 7. I get an error message when I start Windows. After looking for problems, it says that this PC can't be repaired or something like that. When I start Linux, this operating system works fine.

Now I have an SSD hard drive that I would like to use in this PC. There's nothing on the SSD hard drive.

So I created a USB stick on my Mac with the Windows.iso file. I made sure to format the USB stick with .FAT in front of it. When I insert the USB stick into my PC and connect the empty SSD hard drive and select my USB stick with the F12 key, there's only a black screen with an underline on the top left.

The same thing happens with another stick. One has 32GB, which was then formatted to .FAT (32).

If I try it with another hard drive, either this underscore or the error message "reboot and select proper boot device."

Tried the whole thing on another laptop, which has the same errors. I ask for help and am grateful in advance!

The boot sector is still missing somewhere.

https://forum.ubuntuusers.de/topic/mbr-mit-ubuntu-neu-erstellen/#post-8313423

So read the instructions first, then understand, back to the article. Understand
bootrec / scanos & bootrec / rebuildbcd & bootrec / fixmbr & bootrec / fixboot
then the understood instructions for linux and done xD

but then not on the stick but on the plate.

I just tell you clearly: if you shoot your system, you will reinstall it.
rather leave it and try a windows cd / dvd
if you have biscuits, pull "unetbootin" and select the "iso loader" and put the win.iso next to it on the stick