I'm using Windows 7.
Please follow the pictures and create
1. a Mods subfolder
2. place the resource.cfg in the Mods folder
3. create a Packages subfolder in Mods
4. create subfolders in the Packages folder to make it easy to reference items.
The resource.cfg allows you to add up to 5 deep sub-folders from the packages directory.
The Decor folder is sub-divided into 5 sub-folders and one of them is Umbrellas.
I'm not 100% sure but I think you need Ambitions or a later expansion pack for this to work. This setup definitely doesn't work with the Base game.