upload them where? What world files?
I'm very, very, very new to this whole concept, so I'm a little lost.

I was honestly hoping for a hosting site or in-game method to just transfer.
Did this for Minecraft, and it was stupid simple, but it all was an option within the base loading screens.

Sure it works. Just upload the two world files and you are good to go.

AFAIK, there's dedicated servers out there - you can password-protect them and only give the password to your buddies - where you can upload your worlds (read: gamesaves) so everyone can play. So I guess if you transfer the right gamesave all your stuff and buildings and so on should be there? Not sure, though, only been doing this, so far, with completely fresh worlds to start over right from the start. Anyone can confirm this works?