Thanks, but man this is brutal. OK, so I read that whole thing, entered the password, opted in, and then spent 20 minutes trying to find the workshop. Then I spent 20 minutes reading through irrelevant stuff back here in that same thread to read someone else asking where the steam workshop is, and being replied to to check the community page, that it is hidden. Great... so I go back and one by one go through 32 pages of steam workshops and still don't find it, and it seems so hidden that searches for galactic, civ, opt-in, beta etc. are all fruitless.

Then I think mebbe it is in game, so I load up and am prompted to complete a review. If I wrote a review write now after spending an hour trying to find something because it's a secret, my review what be not recommended if you are new because there is a bizarre cult of secrecy around accessing anything! And that would not do justice to the fact that I have been playing for 150 hours and still feel like I have to fight tooth and nail and then search for keys for hours only to finally get to another clue to start the process over. I can't express how unfun tis element of the GalIII experience is. I'm persisting because I see the gem underneath, but man, you guys have to do better than this.

Either make something available, or don't, but don't hide every goddam clue. You need to temper listening to the voices of experience against a control test group who just bought the game to come to your forums and figure out this game and accessing mods etc. and decide how much you want to treat this is still a game in beta, and how much you want to acknowledge that it's on the market now... beta is over, and there are too many hurdles that point to the exit sign for good practice.

Rant over!

I just do it all through the Steam client and subscribe as needed.

As ForesterSOF said, the easiest way is just to view the workshop from the Steam Client and subscribe from there.  In game, the ship designer has a Steam Workshop button at the bottom left that will take you to the Workshop page for ship designs.  On the page where you select your civilization there's a Steam Workshop button on the left next to the Create Race button that will take you to the Workshop page for custom factions.

Some other (or the same) mods are available at Nexus, at this link.

If you're asking how scores get posted to the Metaverse, the game does it automatically when you win or lose.  To see your score, hit the High Scores button on the main menu and be prepared to wait, the servers are slow.  If you are asking how to increase your scores, I don't know, no one has figured out exactly how things like difficulty, map size, etc factor into how the score is calculated.

As for learning how to mod, about the best I can suggest is to read threads in the GC3 Modding sub-forum, here.