Read this in other languages: English, 日本語, 简体中文.

Install

Download the latest version and uncompress it.
Upload all *.mo files to <Your Typecho Directory>/usr/langs . If that directory doesn't exist, you can create one before uploading.
Go to admin > options > genral options, there will be a language selector shows below.

How-to

Fork this repo and clone to local.
Start your translation road by using PoEdit or other gettext software. The message.pot file contains all recent translation strings, but it is in Chinese, so you might want to start with the English translation file en_US.po and update the missing messages from messages.pot.
Push update to your forked repo, and then pull a request to offical languages repo: named typecho/languages.