Sidney Schwartz wrote on Jan 13^th, 2017 at 8:49pm:

Now I'm trying to figure out how to load an FS flight plan into the FMC. I did read both the manuals before asking these questions, and the only explanation I could find for the FMC was a description of what the various buttons are for...nothing at all on actually programming the thing. I use Boeing FMCs on other planes and most of it looks familiar. A flight plan is loaded and shows in the GPS. The plan is saved in the default folder for FSX flight plans. On the FMC I go to the RTE page, press REQUEST SEND and FLTSIM FPLNS, and none of my plans show up. I tried copying the flight plan into the FSX/Captain_Sim/777/Flights folder, but the results are the same. What's the trick?

The CDU/FMC should see, and load, any default FSX Flight Planner flight plans saved in the Documents\Flight Simulator X Files folder.
The other Flight plans that it reads, are the ones you create, or load from the Documents\Flight Simulator X Files folder, and save as a .rt file from the CDU (save routes are found in the FSX\Captain_Sim\navigation\routes folder).

So how are you creating the Flight Plans/routes?

I program the CDU/FMC for the Captain Sim 777 the same way I do it for the rivals 777-200LR/F.