The parts of telescope can differ in varying telescope designs, but they work by using mirrors or lenses as reflectors or refractors to magnify light. Learn the parts of a basic telescope from an observatory director in this free astronomy video.
So, you have a telescope. I don't know whether you have a refractor or a reflecting telescope, and there is a wide variety of telescopes. The basic telescopes, though, are either a refractor or a reflector. Now, we think of a refractor as the old type that pirates use. This is off of a fairly cheap telescope that we've had around the observatory for about twenty years. And, it has a lens in the front and a lens in the back, the light comes through the front and it focuses it out the eye piece. In a reflecting telescope, it uses a mirror instead of a piece of glass. They both do the same thing. They both form a light cone, light hits the mirror, bounces off, and comes to a point and you intercept that point with an eye piece. They both are light buckets. They gather as much light as they possibly can, based on the diameter, the diameter of the mirror of the lens. So, think of a telescope as a light bucket.