The first (and only) step is to create a folder. Name it whatever you want, in my example I'll use stuff. Place a period at the beginning of the folder name, making the final name of the folder .stuff. The preceding period makes the folder hidden in Linux. Now with my desktop in view, hold down the 'ctrl' key and tap the letter 'H'. Voila! Use this key combination to toggle between your stuff folder being hidden from view and shown. The only other thing is to place your contraband into that folder and admire your handiwork. The contents of this folder needn't necessarily be illegal or immoral, maybe you just want to maintain a tidy desktop.
P.S. I know this isn't really secure, but in my house/work there aren't any people that are intimately familiar with Linux. This is a good deterrent as this trick doesn't really exist in windows.