Each NAV radio has two frequency windows(side by side), the window on the right is the standby location and the one on the left is the active window. The standby window is the only one you can tune. Once you have the correct frequency in the standby location, hit the switch between the two windows to place the frequency in the active window. Below this in NAV 2 and it works the same way.
I don't have FSX so my explanation is based on the standard radio stack in most aircraft.
Visual Flight path only works on VOR radials, Localizers and ILS, it won't work with the GPS.
The frequencies are on the map mode, click the airport symbol for the ILS frequency or the VOR for the VOR frequency.
PS You also have to select it from the top menu and choose an altitude( only good for one).
Last edited by CRJCapt on Mon Feb 19, 2007 9:34 pm, edited 1 time in total