you got a real one? no clone/counterfeit? Lets assume you did buy the wcdma snapdragon800 and not the TD-lte tegra4

download multilang rom for cranco wcdma, and transfer into phone storage with pc and data cable first!

On the device you should got into settings, slide to the right tab so "all settings" is highlighted. Scroll down to "about phone" press once on the systemupdate arrow, once done a search, press menu button! select installation pack than browse to downloaded rom and update, after fully updated please do factory reset righ after flashing the update! it removes older files from the old rom!

make sure you backup anything important to you!