How can I update from amber to black?

[Romualdo Ducon]

I got a Nokia 920 amber crimson red unbranded.
with a firmware : 3047.0000.1326.2001

in the box it said it's from Nigeria.
I see the availability updates of Nokia black. Lumia 920 is available for update. I try to update mine but it said that no software updates checked 2 seconds ago. How can I update my amber to black?

 

[praveen_varma]

use nokia software updater and install , else change your phone region to get the update

 

[Romualdo Ducon]

How to change region in my phone?