When a subject is backlit, the usual rule in photography is to expose for the point of primary interest, ignoring the overall background. In some situations, it may be more pleasing to reverse the situation and expose for the background, as is the case here. The most dramatic results are achieved when the subject is simple and has a distinctive shape, as in shadow photography, effectively drawing the eye to the subject. These sorts of images make excellent enlargements and look quite dramatic framed and hung on your wall, particularly when the background colours are appealing, such as soft pastels or even sunset or twilight colours.
You will find that potential subjects abound. What is important is that the overall shape is compelling in some way - graceful or humorous shapes work well. In nature, some excellent subjects to photograph are water birds, or smaller bush birds on branches which can be most appealing. Kangaroo shapes are also very distinctive. In urban situations, the human figure is an obvious subject, as are boats, particularly those with attractive structures and rigging.
I used a very long telephoto lens to create this photograph of a rising sun with grass trees in silhouette [135/600 mm, f11].
An Eastern Reef Egret lunges at its prey. While this image would have been effective either front- or back-lit, it is the simplicity that makes the shot so appealing. The grey uninterrupted background is the reflection in the water of the silver-grey sky against which the strongly back-lit bird and its reflection are silhouetted. [135/600 mm, f16, 1/500 sec.]