I want to build a website in french but I don't know were

Hello,
I want to build a website in french but I don't know were to start. I have a everything, domaine name, Web Hoster, Website Pro theme, Wpmudev membership ...

1) How to build a wordpress site in french from scratch? (with a Cpanel in English if possible) I tried to build one, few weeks ago, but it didn't work because the way too many part in english ( Buddypress specially) and a lot error messages, break-downs, and other issues... So I'm about to delete the hole site and take fresh start in French from scratch.

2) I would like to add an English version of my website later, is that possible? Do I have to take few things in consideration before I start?

Thank you for your precious help.
Best regards,