In nearly all circumstances, you need to place the mod folder in ..\MyGames\Galciv3\mods. There is an "examplemods" folder there, place your mod folder there in parallel with that. Then yes, ensure "use mods" is enabled in options, relaunch game and the mod should be there. Best to experiment with a faction mod, just so you can get the hang of it, as you can see the results right away.
Note, "use mods" should be functioning, if multiplayer is disabled, which currently doesnt allow mods.
