If you want to do that without activating your computer. You can open a picture in Microsoft Paint or Window’s 10’s Photo Gallery app and set it as a wallpaper. You can also if you have used an older computer and saved it as a .

How do I personalize Windows 10 if not activated?

Right clicking on any image file around a non-activated installation of Windows 10 will still provide the option to “set as desktop background,” and the same can be done by right clicking on pictures in a web browser, as well as the “…” menu in the Photos app.

How can I customize my desktop without activating Windows?

Open File Explorer and navigate to the folder where you store your wallpapers. Once you find the suitable image, just right click it and choose Set as desktop background from the context menu. The image will be set as your desktop background ignoring the fact that Windows 10 is not activated.