I am not a code or IT person, but try to share as much as I could here what I have learned from my many mistake here. But I can't promise this is flawless.

I am building a multi language sites.

I found this Advanced front page Modules that very useful.

1/ set up the language setting to Path prefix or Path prefix with language fallback.
2/ create content in 2 language.
Example:
www.example.com/node/1 (eng)
www.example.com/cn/node/1
3/ then go to the Advanced front page Modules setting, choose "redirect" and place this link.
4/ also make sure you place "front_page" at the Default front page: (at the bottom of the setting).

I m sure there are better to do it, but for me, it is a easy way since I am not IT person.