The character you control faces the mouse pointer, and W makes it go forward, and S backwards. to shoot left click. it take 0.5 secs to shoot after the left click, But it doesn't really matter. You can also choose what level to start fro but if you die in level two you automatically go back to the first level watch out for the black squares as they can kill you. If you die at any point in the game you restart from the very beginning.
For gun sound effects: http://soundbible.com/2050-Cartoon-Ricochet-2.html