One of the hardest things about understanding a medical diagnosis is understanding the terminology. Similarly, explaining problematic symptoms to your doctor can be much easier with a basic knowledge of anatomy. In the interest of eye-education (eyeducation?), allow me to direct you to an excellent and informative article posted by AllAboutVision: http://www.allaboutvision.com/resources/anatomy.htm
This article names parts of the eye, and explains the function of these parts in easy-to-understand terms. There’s even an interactive picture of an eye, where you can mouse over the part of the eye you’re interested in and learn more about it.
Need a crash course? Here you have it:
The pupil is the dark center of your eye, and is responsible for controlling the amount of light that enters your eye.
The iris is the colored circle of your eye, around your pupil. The iris also helps to control the amount of light entering the eye.
The sclera is the white of your eye.
The cornea is the clear front part of your eye, and it helps to focus light in the back of your eye.
The retina is a layer of light-sensitive tissue that lines the inner surface of the eye (thanks to Wikipedia for the wording there).
Coolest eye-fact of the day? The retina and optic nerve are actually an extension of your brain, and are considered part of the Central Nervous System, or CNS.