There is a menu Item Help -> MyInfo help which points to the (online) documentation
Relative Links
If you enable the Insert Relative Links option in Tools Options Editing, MyInfo will insert links to notes in other notebooks and to external files relative to the notebook’s file path.
That allows you to move your notebooks around and as long as your linked files are moved with the notebooks, these links will continue to work.
Some example relative links:
file.doc (the file is in the same folder as the notebook)
images\picture.jpg (the file is in the images folder that is in the notebook folder)
..\file.doc (the file is in the folder that is one level higher than the notebook folder)
..\..\file.doc (the file is in the folder that is two levels higher than the notebook folder)