I believe you are using AT&T as your carrier. I have shorten the long link for you to download the Asia or East Asia OS for you: http://bit.ly/3vJ7Uo
!! Once you are there, make sure you see the AT&T logo before proceed.
Then choose 9800 and click "Next"
You will then see a few packages but 2 in particular. One says "Asia" and the other says "East Asia".
Try one before trying the other.
Download the package into your computer and then run the package from there.
Once completed running the desktop manager will show on your computer desktop.
Then connect your 9800 to the computer.
You will then see, in "language support" and "language input" Chinese is available for select.
Add them for update into the 9800.