This is the simple one, which involves extracting a ZIP file.
If you don't trust that, use the homebrew method instead.
Here are the steps:
1. Download the file
2. Extract the ZIP's contents onto the root of the flash drive
3. Download the AUTOEXEC patcher
4. Drag your USB drive onto the patcher
5. Plug the USB drive into the target computer
6. Turn on the computer, making sure that it boots off of the USB
7. If you see Windows 3.1, that's a success!