So, I hope the disk is detected by Gparted. I don't know the type of the disk and connection, i.e. USB, Firewire, e-sata, ...
If the disk is now all empty (=unallocated), you must see it in Gparted: it must be drawn in grey, and marked in the table under the graph "unallocated" with its entire size.
You choose the unallocated space and you click for a "New partition".
Leave about 50 sectors at the starting point (give the start sector number 50 units bigger than the initial value). This is normally needed for ntfs, but this loss is very small. If you give the size in MB, you give 1MB as preceding space.
You choose "Primary partition" and "FAT32" as filesystem.
After that, you give "Apply".
Leave Gparted do the work (it must be very fast, just a few seconds, as the entire disk isn't erased sector by sector, only the filesystem structure is created).
Next, check the information about the new partition. Take your time before rebooting, because cache content needs perhaps some seconds to be written. So, reboot 1 minute later.
When you reboot in windows, you have to see the new disk.
I sometimes had an external USB disk not directly detected on the restart, I had to boot windows first, and then plug the usb cable and turn disk "ON" to be detected.
In windows you can open the "Disk Management" to see how the system understands the new disk: size, filesystem, letter (name).
*** It is highly recommended to backup any important files before doing resize/move operations. ***