Windows 10: New Theme: Cumulus

There were some nice clouds today, so I took their pictures....

And then, I put them in a folder named DesktopBackground, (It's a Dword, not an error!) and then that went into a folder named Cumulus. And then I navigated to C:\Users\Ray\AppData\Local\Microsoft\Windows\Themes, and then dragged that Cumulus folder into Themes, and dropped it there.

Next, I opened the Themes folder, opened the Cumulus folder, opened the DesktopBackground folder inside it, selected all the images, right-clicked on one of them, and chose 'Set as desktop background' and up came the first one onto the Desktop. Now, open Personalization, choose Themes > Go to Theme Settings, and when the window displaying all your Themes thumbnails opens, find your newly installed theme in the upper left corner. Right-click it to open a dropdown allowing you to choose 'Save' and give it a name. 

Because there's eight images in this theme, you will want to choose a time interval for each to display on screen before changing to the next, and the quickest way to get at that is to ask Cortana "Change desktop background".
You will be shown the window with the choices for adjusting the timing. Pick the one that suits you, and remember to "Save changes" before you leave there.

And you're saying "That's almost but not quite exactly like we did it before, in Windows 7 and 8, and 8.1, isn't it?" And the answer is "Yes, that's a definite Maybe!" So now you can close all those open windows, and enjoy your new theme. Or, you can find a bunch of different pictures, size them to fit your Desktop native resolution (your screen size!) and use those instead, now that you know how. This is your Windows, so don't be afraid to personalize it.