You can import a selected MPX 4.0 file into either the current map (under the selected topic) or to create a new map, if no map is open.
If you are importing task dependencies as Relationships, and you expect to have many of these on the map, you may want to set the default format of Relationships to a light color and thin lines. You can also do this after import.
Click the File tab, click Open, and then in the Files of type list select Microsoft Project Exchange File.
In the dialog, select the MPX file to import.