-->How to (manually) edit NavData files?

How can we manually edit the NavData files of PIC767, in order to "manually" add a waypont, for example?I have been trying to add a waypoint not listed in the latest Airac Cycle, by using real Lat/Lon data, with the Notepad (as it is a text file).But upon entering the FMC, it still gives me error, "Not in Databse".What am I doing wrong? As it is a simple text file, why dont the entries I make using notepad, appear in the FMC database upon using it?Regards, Marcelo Santiago, ChilePosted, Saturday, 11.30am EDT