where are you from?
most of the b510 release were in western europe and when i remember right in romania (maybe in the neighbor states too) through OTA (automatically through system update function..
the other option is to download the b510 from different sources mentioned in some threads here..
then you can, depending on what you downloaded, update through local update or by updating through force update method..
just read some threads concerning the update to b510 carefully and you'll find what you're looking for..
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HUAWEI Ascend P6-U06 B512 - TWRP Recovery - build.prop mods - earphones volume tweak