Users on the Fast Ring on Windows 10 Insiders can download build 15007 for both PC and mobile. Seems we just had a recent build come out…. I’m not complaining!
[Coming Soon] Download themes for your PC from the Windows Store (PC): In Build 15002, we introduced the new themes settings page in the Settings app. Soon, you’ll be able to go directly from the themes setting page directly to the Windows Store to download new themes for your PC! This isn’t working yet in today’s build and you’ll see a Store icon that does nothing at the bottom of the themes setting page. However, you can go to the Store page for themes here to try out downloading themes from the Store.