When taking pictures, a subject in the very middle of the frame is very boring and not considered a very good picture. To make your pictures better in general te need to take into account the Rule of Thirds. Here's a primer.
Camera simulator designed to teach basic photographic principles. Use it to experiment with otturatore, dell'otturatore and aperture settings, film speed and camera shake.
"Photography is the power of observation, not the application of technology." Great tutorial for the beginning photographer and a nice refresher for the skilled veteran.