Win-10 Desktop

I fired up my Win-10 for the first time and up came a sort of bland desktop in blue. So I right clicked to personalize and unless I am looking in the wrong place, I see a choice of 4 awful backgrounds and none of them rotate between different scenes. Whats up with that?? Where are all my choices like before? Is there a way to get nice slide show backgrounds with Microsoft provided pictures? Are they hiding on this computer somewhere? By the way I do not have my own folder of pictures. I do not take pictures nor do I want to start.
This will probably be an on-going thread as I proceed through this new OS.

When you right click and select Personalize, click on Themes on the left. Then in the next screen click on "get more themes in the store." There are hundreds to choose from.

Store? As in purchase? No way.

I don't think you have to purchase the themes.
You didn't with Windows 7 and 8.
Did you check here?
https://support.microsoft.com/en-us/help/13768/desktop-themes-featured

No, they have hundreds of themes for free. It used to just say "get more themes online." The Store has tons of free games and apps.