Ah Guitar Hero huh? It's awesome. It's just like DDR. But your controller is a guitar. There are no strings on the guitar but instead there are colored buttons. You have five buttons Green, Red, Yellow, Blue, and Orange. As the notes come down on the screen you have to hold down the right color and hit the strum bar when the button is in the right area. (just like the arrows on DDR) Here is a video to show you what it's like Misha. And don't get intimidated by the video. It's on an expert setting.
http://www.youtube.com/watch?v=VgVG73TE0Tw