You have a domain in OVh and you'd like it to point to your dedicated server - your server will be DNS for your domain.

How?

• If domain is registered in OVH

Log into Manager and choose Domain name.
Choose your domain and click "Your DNS servers". The next page allows assigning new DNS:
Insert : nsXXXX.ovh.net in 1 and ns.ovh.net in 2 (the order doesn't matter).

• If the domain in registered elsewhere

Log into the registrar's control panel and change DNS configuration:
Insert : nsXXXX.ovh.net in 1 and ns.ovh.net in 2.

Conclusions
After confirmation, you need to install your domain on the server and on ns.ovh.net.
Those manuals may help you with these operations:

• InstallSecondaryDNS

• InstallWebsiteOnDedicated

• CobaltInstallDomain