Are the parts really tiny? If so they are the ball detent and spring that allow the aperture to "click" in place. When you rotate the hood on the sight you should feel it click into position. If your sight does this now, then the parts are already installed and your parts are spares. The spring clip that holds the hood to the sight ramp sometimes fails or comes off, the hood falls off and the spring and ball detent go flying.
If the hood freely rotates without clicking then you need to remove the spring clip and install the spring and detent.