Oh, okay, first off, this is one of the EASIEST achievements in the game! (Well, if you have the full version). Okay okay, anyways, enough of that stuff, now onto how to win it: simply collect, as the achievement says, collect 50 stars throughout the levels. And yes, these can be in different boxes. When you start the game, like when you're on the boxes, the top left corner says how many stars you have. When you've got 49, you'll be super excited. (Most likely). I was. Anyways, the easiest boxes to do this in are the first and second boxes of the game. But, again, you need the full version. Okay, that's it!