Go to the WinUAE website and download the installer-file.
This tutorial is for WinUAE 0.9.92, but it may work with other versions too.
Buy it from Cloanto, search Google or transfer it from your real Amiga.
There are six disks: Install, Workbench, Extras, Storage, Locale and Fonts.
Buy them from Cloanto, search Google or transfer them from your real Amiga.