After logging in to the controlpanel you can find the button "White label" in the menu on the left.
This page gives you access to all the White label functions: Customer settings, Layout settings and Marketing materials.
You can add/manage customers (subaccounts) here.
Add customers :
For every customer (subaccount) you can setup the access rights.
A subaccount only has access to the specific access which you gave to that customer.
Adjust the controlpanel colors to match your own business.
Adjust the logo for the controlpanel, emails and login page.
On the White label page you can find the White label marketing materials for your website.