In WordStar I think you used .fi. But I forget.

In Word, if you want to include a text or document file (typically a .doc)
you use a field

{ INCLUDEFILE "the_full_path_name_of_the_document" }

You can insert the special {} using ctrl-F9. The backslashes in the pathname
should be doubled, e.g.

{ INCLUDEFILE "c:\\mydocs\\myfile.doc" }

If you need to insert a picture such as a .jpg, use

{ INCLUDEPICTURE "c:\\mypictures\\myfile.jpg" }