How to enable start backgrounds?

[vgSefa]

Hello,

Yesterday i have brought a Nokia Lumia 920 and it's using Lumia Black (OS version 8.0.10517.150)

I want to enable the feature that explained at Wpcentral as "How to get beautiful Start backgrounds for Windows Phone 8.1" (I wanted to give a link but system is not allowing me to insert links) but when i go to Theme settings there is no "Choose photo" option.

How can i enable that?

 

[vgSefa]

link here

How to get beautiful Start backgrounds for Windows Phone 8.1 | Windows Phone Central

 

[mpt15]

You will need to update your phone to windows phone 8.1

You can either wait for the final.release to your region and/or carrier; or you can download the preview for developers.

Edit: see this: http://www.windowscentral.com/how-sign-windows-phone-81-preview-developers