Instructions for uninstalling mods from the Steam Workshop: Accept to reload when returning to the main menu, so that the downloaded mods are loaded.Make sure it is checked / enabled after it finishes downloading.You might see a download progress bar in the list item if it takes a while to download. Return to the game, and you should see the mod listed in the Workshop mods list. Browse items in the workshop, and when you see a mod that you like, click on the 'Subscribe' button. The Steam overlay will open and show the Workshop.
Instructions for installing mods through the Steam Workshop: