It's basic, it's simple and it's created to keep your workshop files safe. Readme has the full guide on how to properly use it. This is created to store VPK files from Left 4 dead 2 to keep them safe in case valve were to take down the original mod page for the Addon. Replace the (FileName).png with a different image and rename the VPK to the same name as the file and bam you got yourself a stored weapon you can put into the addons folder at any given time.
I suggest using this to download VPK files: http://steamworkshop.download/
This is an example URL you can use to download the VPK file and make sure to save the .png file as well: https://steamcommunity.com/sharedfiles/filedetails/?id=710412915
Only .png .jpg .jpeg are supported
Mild Cartoon Violence