You can get the AuthCode for your domain from the the provider your domain is registered with.
Domain is registered with Jimdo
If your domain is registered with Jimdo, we will send you the AuthCode. Simply send a message to our Support Team and let us know which domain you need the AuthCode for. Our Support Team will get back to you as soon as possible and tell you how to proceed.
Domain is registered with another provider
You can request the AuthCode for your domain from your external domain provider. Reach out to your current provider's support team or find out how to get the AuthCode from their online help. All further steps should be explained to you then.