Do you want a custom ROM or just a stock one with your language on it? If you want a custom ROM, then do the following:
This is how you boot into bootloader: Hold the power and volume down buttons simlataneously until the screen goes dark then keep holding the volume down button and release the power button. You can use the volume up and down to go up and down the menu and use the power button in order to enter, so enter Fastboot mode, it should display FASTBOOT USB if you're connected using your USB cable.
When you are in bootloader, click on Fastboot. After you are in Fastboot USB mode (it will show that on the screen), unlock the bootloader using this tutorial:
http://www.redmondpie.com/how-to-unl...ader-tutorial/
After you are done with that, you'll need to download TWRP 2.5.0 and place it inside your fastboot folder on your computer, and then open a command prompt window from there (shift + right click and open command prompt window here) and then execute this command:
fastboot flash recovery recovery.img
Of course you replace recovery.img with whatever the name of your recovery is, in that case TWRP 2.5.0's zip file.
After flashing the recovery, reboot back into your Chinese ROM and plug the USB cable in so that it will show the device on your computer. Open the device and copy any ROM.zip you downloaded to the Downloads folder, and then boot back into recovery and install it.
If you want to remain stock, you'll need to get the proper RUU for your device and install it. When you are in fastboot, use this command to get the CID of your device so I can see which RUU can be installed: