During creation of family tree, GenTle automatically creates family records. You don't need to care about family members. If you want to browse family records created by GenTle and/or add some information (e.g. notes), you can open Family Browser dialog. You can open it via menu/tool-bar button for all families in the system. If you want to open family browser just for one person and view families where the specified person takes place, right-click on a person and select Families menu item from View menu.
Since GenTle creates family records automatically, it is not possible to add families manually, as well as delete them or add and delete their members. You can add only some information about families when editing its record in Family Browser dialog.
There's a bug in family algorithm. It determines families and family members correctly but during family creation, it can forget information added manually bu the user in some cases. To correct it, family algorithm must be re-designed and it will take some time :-(.