You have to check what are the export options found in the NoteMap application, then based on those files import them back into Opal. Since there isn't enough information about this procedure, I recommend you access NoteMap's main menu, then File and check for Save as or Export function.
You can do the same for Opal, but this time choose Open or Import. I believe you will find a common file format supported by these applications to import the data from one to another.