Adding a virtualhost to your instance from the domain's control panel
If your domain name and instance are both on the same Gandi handle, you can add an address from your domain's control panel whenever you want.
To do this, you'll see the following on the right of your page:
Gandi Cloud VPS Hosting: Manage
Click on “Manage” to call up the page where you can modify your hosting addresses.
Look to where it says Simple Hosting:
Just choose the instance, the sudomain (ex. www) and then click “OK”.