Build etsy like website with multi-languages

I am trying to setup an Etsy style marketplace website by following the tutorial:

https://premium.wpmudev.org/forums/topic/how-to-build-your-own-etsy-like-site-using-marketpress

My main question is:
1. I would like to setup this website with multi-language environment and each store owner/user can choose their language preference.

2. Each page should be able to display in different language.

I couldn't find the information anywhere so if anybody can help with this, I really appreciate it.