Uploading Your Theme

Theme Developer Dashboard

This is a menu accessed when you're in the "Themes" menu, and in the bottom menu bar, click "Develop Theme". Your theme should show in the list of WIP Themes, if you've actually put it in the right folder... (check the introduction of the tutorial).

If you click it, it'll take you to a new menu which shows all the information of your theme, and the menu bar shows you some useful tools.

"Upload to Steam" -> Takes you to the menu that lets you upload your Theme to the Marketplace (Steam Workshop), and thankfully it is a One-Click thing.
"Reveal in Finder" -> Opens the Theme's directory on your machine.
"Use (Preview)" -> Equips your theme for previewing, but requires a Scene Reload to take full effect, as with any other Theme.

You'll want to click "Upload to Steam", and after clicking the second upload button, navigate to the directory in which your Theme is, and it should upload fine! Now it will take you to the page of your Theme, since it's privacy settings are on Private by default to allow a player time to make sure the item page looks exactly how they want (this most likely will not affect any in-game downloader shit.)