Instructions
Play through "Kirby's Epic Yarn" until you defeat the final boss. Collect as many beads as you can; these are colored circles scattered throughout each level.
Go back in each level and collect any beads you missed in the previous levels. A bar appears on the top of your screen when you're fighting the final boss. As you collect the beads, the bar fills up more. If the bar is filled when you fight the boss, you will unlock the first secret level.
Fight the boss once you have enough beads to unlock the first level.
Play through the first secret level. Completing it automatically unlocks the second secret level.