First themes for Windows 10 available in the Store for Insiders
Microsoft publishes themes in the Windows Store
Windows 10’s Creators Update in Spring 2017 will officially bring themes to the Windows Store, but even now Insiders on the Fast & Slow rings can try them on their PC. Microsoft showed themes in the Store during October’s unveiling of the Creators Update, but the feature has not been formally announced.
The new themes for Windows 10 are currently available for anyone running Windows 10 14951 or higher. After installing and activating, they change wallpaper, accent color and sounds in Windows 10.
Download a theme, go to Program Files\WindowsApps, find the folder name of the theme and click on the file.
Windows 10 Themes: