Before uploading your mod, first create a directory/folder for the mod on your computer. Inside this directory, make sure the structure of your module folder mirrors that of the Neverwinter Nights: Enhanced Edition game directory. The location of this module directory is up to your discretion.
Using the example above:

We named the mod “My Steam Module”


Inside this directory, add an extra folder.


If specific file-types have proper folders in the Neverwinter Nights: Enhanced Edition install directory, add a seperate folder for those. For example, if we use Hak packs in the module, include that file inside a new folder:


Continue adding folders for any files your mod needs (.mod, .wbm, etc.). To add a thumbnail for your mod, include an image file named thumbnail.png or thumbnail.jpg in the root folder of your upload.

Steam allows you to tag your mod with a list of categories that can help users find your content. To add tags to your mod, add a file called tags.txt in the root folder of your upload. Add a new line of text to the file, where each line is the text of the tag you’d like to add. Make sure there are no blank lines.

Here is the list of pre-defined tags you can use:

In order to upload your prepared folder, enter a specific console command from inside a Steam-enabled version of the game.

• Launch Neverwinter Nights: Enhanced Edition from Steam.
  
• Open the console (press ~)
  
• Type: WorkshopUpload <full path to your mod directory>
  
  In our example, in this case it would be:
  
  WorkshopUpload C:\My Steam Module
  
  
• Steam will upload the mod and display a message when complete.
  
• Close the game and go to your Steam Workshop content directory. You should see a new content item with the name of the directory you uploaded.
  
• In Steam, fill in the description and any additional data for your mod

Steam Workshop requires that your Steam account has spent at least $5 USD before posting content.

You may update your mod by following the same process as uploading. As long as the name of your mod is the same as the name of the directory you are uploading, Steam will detect that the mod is the same, and replace the files on Steam Workshop with the ones in the directory.

“Subscribing” to a Mod on Steam Workshop sets Steam to download that workshop-item, and to keep it up to date. It is the method by which you may download other user’s Mods.

To subscribe to a mod, navigate your Steam client to the Neverwinter Nights: Enhanced Edition workshop interface. Then, find the workshop item you would like to subscribe to, and click “Subscribe”.

The next time you start the game, the mod content should appear as long as it was structured and uploaded correctly.

If your mod relies on content from other mods, you can use Steam Workshop's dependencies feature. To do this, go to your workshop item's page and click "Add/Remove Required Items". From here, you can choose other workshop items that your mod depends on.

Using this feature will allow you to avoid including redundant content or content that you don't have permission to redistribute.