I also use OVH for my server, but my DNS is hosted via CloudFlare and my domains are (for the name servers) at NameSilo (the registrar). The NS's at NameSilo point to the DNS servers at CloudFlare.
The public_html directory should be in your /home/<yourusername> directory - but that's if you have set it up that way. If you have not, then your files typically go into /var/www or /var/www/public_html.
The base directory (referred to as DocumentRoot) has to be defined in the Apache vhost definition stanza or vhost file.
If you don't have everything working, and don't require a panel (cPanel, etc) then I'd suggest getting your DB exported back out and saving it locally along with your files (for any sites you have existent) and then re-imaging the server with CentOS and then use CentMin Mod. It uses nginx for the HTTP server and is MUCH higher in performance than apache is.