Step 2: Use the photo
Close your Notes function, and open the Photos function.
Find the screenshot of your note in the "camera roll", and bring it to full-screen.
Tap the screen to bring up the menu options, then hit the "share" button (bottom left). From that menu, select "use as wallpaper", and then select the "Lock Screen" option.
Your note will now appear on your iPod's screen when it is switched on.