Adding languages to the client?

I recently started playing on warmane from the US, and I've met a bunch of wonderful, friendly folks. I'm a Chinese-speaker and I've had the opportunity to meet a bunch of friendly Chinese players who don't know any English, so we have to communicate in Chinese.

The client I downloaded doesn't display chinese characters when they type them at me, and I'm wondering if any of you know a way to change that. Right now it just gives me a bunch of ??????? kind of things when they type them at me.

Is this a simple matter of adding a language to a text file somewhere, or is this too much work to bother with?

To clarify, I do not want to change my entire client to the Chinese version, I just want my English client to be able to display Chinese characters.

Thanks!