XwolfhoundX

I can see a NAV knob there, but I don't really understand as to what FMC L, FMC R, CDU, CDU C means.

I'm having trouble using the FMS of the default 747-400 that comes with X-plane 10. Can anyone teach me how to use it properly?, I have been trying to figure it out for awhile. So far I have managed to input VOR, APT, FIX codes but I can't seem to get the plane to follow the defined routes. I have heard that you need to switch the NAV selector knob to GPS but I can't find that knob in the cockpit. Thanks alot EDIT: This website does help http://home.earthlink.net/~x-plane/FAQ-Using-FMS.html, but in a limited way as the layout of the FMS is different from the one in the mentioned aircraft. I do appreciate if anyone can provide help for the 747-400 FMS, thanks again.