You can manage your email accounts from the administration interface at https://zimbra.ossds.net:7071/zimbraAdmin/.  Only users that have been designated as administrators for your domain can login to the administration interface.  The Manage Accounts pane is the first thing you will see when you login.  In the upper left corner of the Manage Accounts pane click on the New button and this will start the wizard to create a new email account.  Field with a * are required fields.  Make sure you enter a password for your new email accounts.