As a mad bush pilot I can't help with using the nav-aids. You said in your original question that there's "a blank space for the GPS". This doesn't sound right. Pity it's a big download or I would check it out for you. I'm surprised it has no GPS on a pop-up window like the defaults. If it doesn't have one you can add it yourself. Check out my tute.
http://www.simviation.com/lair/AddGPS.htmPS. I just realised the version you have is for FS2004. The default GPS has a different name to the one in FS2002. You should be able to fix that panel for FS2002 by changing the gauge name in the GPS Panel.cfg entry. It should look something like this.
[Window02]
size_mm=150,250
position=8
BACKGROUND_COLOR=16,16,16
VISIBLE=0
ident=GPS_PANEL
gauge00=
gps!gps,0,0,150,250
It might be better to download the FS2002 version of the aircraft.