This video shows how to publish a level to Steam Workshop. Publishing is done via the level editor and will upload the contents of the level folder to Steam Workshop.
Once a level is successfully published, it will be assigned a workshop ID. Subsequent publishing will in fact edit the existing Steam Workshop item associated with the level.
If for any reason you want to create a new item instead of updating the existing one, make sure to check the "Publish as new item" checkbox when publishing.
To be able to access a custom level in Gorescript, you must be subscribed in Steam Workshop to that level. Once subscribed, if the level doesn't show up ingame in the "Custom levels" menu, restarting Steam should fix it.
We're also happy to announce we're available on GreenManGaming with a 15% launch discount!