I'm afraid you need to contact Homestead for specific directions on setting up your account, you should get in touch with Homestead by logging in to
http://helpcenter.homestead.com/ with your Homestead account and password, or by calling their main customer support line: 1-800-710-1998. Zimbra is only the software supplier and have no knowledge of the set-up requirements for your email client, Homestead will be the people responsible for providing the details.