Chinese WP

I want to build a WP blog website and my main audience are Chinese people who do not read English. Therefore I want all the default words to be in Chinese. I searched and this is the only solution I found:

in the file “wp-config.php”, change “define(‘WPLANG’, ”)” to “define(‘WPLANG’, ‘zh_CN’)”

But this did not change anything. Everything on my website is still in English, such as:
“RECENT POSTS”
“This entry was posted in XXX on 10 April, 2013.”

I want everything to be in Chinese. Please help me. Thanks.