The interface of both editors is purely functionalistic - functionality is most important here.
Language box - here you set the language settings - whether it is case-sensitive, for which doctype it is and data file version.
The mark-up language definition files have .Tag extension and should be stored in Tags & Languages sub-directory of your InSite Constructor directory so that InSite Constructor can use them.
(The text boxes are at the top so that the editor window may be placed somewhere at the bottom of the screen (the lists will not be visible) and the rest of the screen may be occupied by some definition files or anything you get the information from. The lists are not necessary to be visible when adding new items. Then you may move the window so that the whole editor can be seen and work further with the elements, attributes and values.)
Type the language words in the boxes here.
The language definition files have .Language extension and should be stored in Tags & Languages sub-directory of your InSite Constructor directory so that InSite Constructor can use them.