Select Add Owner ... to display the Add Owner dialog box, which allows you to specify the permissions you are granting to the owner of the active ACL's object. If the menu item is dimmed, it means you already have this entry on your ACL. You can have only one such entry on an ACL.
Select the permissions you want by clicking on the desired permissions displayed in the Permissions box. Note that if you do not select any permissions, no permissions are granted and no access is allowed.