Adding a folder for images is described in the article management manual very summer. Chapter 8 and Chapter 20.2 describe how you can easily link the images.
System administration> System management articles> Article images
-First create a main library, this is a path on your network (note that the print manager must have access to this path)
-You then create a sub-library, which hangs under the main library
The tip is always to see how things are now and to create the new one in the same way.