DNS domain mapping system heal statut invalid


I have setup the domain mapping with success.

I d’ont have understand how to configure now the dns.

I have 3 websites : http://www.site1.com http://www.site2.com http://www.site3.com that i will for all use the same wp systeme. I use Plesk as server manager, and i’am in OVH registar. When my configuration is ok on my first website : http://www.site1.com now i have to change what ? the dns on registar or the dns on plesk server (all A pointed actually to my server adress IP)

I don’t need so tu upload wordpress in each hosting space on my server ? i just need to configure DNS ? What is the good DNS (i have read the tutorial but don’t understand)

Finally, if i will have differente templates on each domain but using the same wordpress its ok with this plugguin ?

Thanks for your reply