If you are wanting the second of those two scenarios, then I can help. I am not sure how the first scenario would be carried out.
Assuming that you want to burn the Windows 10 installer to the USB drive to install on another computer:
First ensure that /dev/sdb is indeed the USB drive to which you want to burn the Windows ISO. You can use
to find the drive, and see the mountpoint for partitions on the drive. If any partitions on the USB drive are still mounted, run the following, replacing [x] with the letter and [y] with the partition number.
sudo umount /dev/sd[x][y]
You can then burn the ISO to the drive with this command, again replacing [x] with the drive's letter
sudo dd bs=4M if=/home/1mies/Lataukset/1.iso of=/dev/sd[x]