The Boss is hiding behind the rocky bricks. You can only destroy the bricks with the Missiles.Colored bricks are your friends.Don't just kill them but use them to find Power Ups. You can find additional Lasers, Missiles, Lives and Shields. You'll have a greater chance to find something valuable if your Ammo runs low. Certain colored bricks give certain Power Ups (Blue bricks give you the Shield and so on).