Making a FOLDER INVISIBLE is very easy.
Just follow these steps,

• Make a folder on your desktop.
• Right click on it and then click on RENAME

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• Then by holding ALT key from your keyboard press 255 from your NUM PAD and then release the ALT key.
• Now the name of the folder will disappear when you click anywhere on your desktop

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FOLDER NAME DISAPPEARED

• Now right click on the FOLDER and click on the PROPERTIES>>CUSTOMIZE>>CHANGE  ICON.

• Choose the INVISIBLE ICON as shown in the below Image and click OK.

• Now your folder will DISAPPEAR and you can put any file you wish to as we normally do!