SteamCMD can be downloaded at these URLs:

Windows: https://steamcdn-a.akamaihd.net/client/installer/steamcmd.zip
For Linux and macOS, visit this page and follow the provided instructions.

Extracts the contents in a desired folder like C:/SteamCMD and launch the SteamCMD executable/script.

A VDF file is essentially a text file that contains instructions to follow or fields to fill for SteamCMD.

Here's one for DEADBOLT:

Save this in a text editor of your choice as a file with a .vdf extension and you're good to go.
Alternatively, download a readily-made .vdf here.[file.garden]

• appid - DEADBOLT's Steam appid, don't change it.
  
• previewfile - The thumbnail of your map on the Workshop. Ideally has to be 512x512 and under 1mb, follow those guidelines just to be safe.
  
• contentfolder - the folder that includes everything you need to upload. For example, a single file upload with the contentfolder that's listed above looks like this:
  
  
• visibility - 0 = Visible, 1 = Friends only, 2 = Hidden
  
• publishedfileid is, naturally, the file's id. Leave it at 0 if you're uploading it for the first time to create a new Workshop page. If you want to update an existing map, replace the 0 with your map's Steam Workshop ID.

As mentioned previously, launch SteamCMD and you should see this terminal window pop up.



Log into your Steam account by typing in:
Keep in mind that this will unlog you out of your account in the Steam client, and you'll have to relog back in once you're done.

Once logged in, input this command (mind the quotation marks ""):

If done correctly, you'll see a successful upload reported in the terminal and your map should be displayed on the Workshop.

Same principle applies as when uploading multi-stage levels in the level editor: the first level has to be the first in alphabetical order, and there have to be transitions between said levels.

Other than that, just drop your .nc files into the contentfolder that's listed in the VDF, and you're good to go.

To update your level, simply replace the 0 in publishedfileid with your map's Workshop ID, which you can always find in its url.

Any changes that you made to the thumbnail, the .nc file, or the contents of the upload folder as a whole, will be reflected in this upload, so be careful.