Use the Office 365 setup wizard to configure basic Office 365 services (such as domains) for your organization in just a few steps. These steps work for business, government, nonprofit, and educational customers.
Verify your domain.Use the setup wizard to add your custom domain (like www.contoso.com), and verify that you own the domain.
Sign in to your Office 365 account, then click Domains on the Admin dashboard.
Choose Add domain to start the setup wizard, which guides you through verifying your domain and other setup steps.