Instructions
Allow the game to load to the main menu. Walk up to the PS3 controller on the screen and press "Square" to interact with it.
Scroll to the "LittleBigPlanet" option, which is the center icon. Scroll down to the "Community" option and press "X" to select it. This shows a variety of icons on the planet in the distance.
Move your cursor around with the thumbstick to highlight the different user-created levels. Press "R1" to see more levels. When you find one you want to play, highlight it and press "X" to see its menu. Select "Play Online" or "Play on my own" to start the level.