Adding your Scenario to the Workshop is very simple, first make your Scenario and test it thoroughly.
In order to not break any saves, Scenarios cannot be updated after being published so make sure everything is working as you intended before uploading to the Workshop.

When you are ready, load your Scenario in the Scenario Editor and open the Workshop Window.


Then click Upload.


And if everything went well you should see a "Upload Success!" message.

If you want a custom Workshop Thumbnail, before you upload go into your Scenario folder which should have a name similar to your Scenario name and add a 256x256 image named preview.jpg

That's it! If everything went well your Scenario should be available on the Workshop for anyone to download and play.

On the Main Menu the Workshop Scenarios have a little "W" icon next to them.


Now go make something great! I look forward to trying out your Scenarios!

Cheers!