The controls are simple.
All you need to do is press the arrow keys in the direction of the blocks that appear.
For each time you press the arrow keys a block will dissapear.
Pressing an arrow key where there are no blocks, or the bar is too much shorter than the others, will cause you to loose a minimal amount of points.
This game uses formulas to make it when the blocks appear, which essentially means that this game can use any song. Which means you can play any song on Newgrounds, all have to know is it's ID.
Remember, though, that this is a beta game, so if there is anything that doesn't work or you think should be improved, all you have to do is leave a review saying so. I will take your advice and most likely change the game for the final release.