I have mentioned before that the eye will always go to the brightest parts on an image first. Black and white images where edited by dodging (lightening certain parts) and burning (darkening certain parts) them, yes image editing is nothing new.  We too can use brightness compositionally to attract the viewer's attention to the part of the image we want them to go. Look at this image below; what attract's your attention, where do your eyes keep on going back to?

Yes, it is the bright green in the background. Now this scene was naturally lighter there than elsewhere in the image. What if the next image did not have nature's help? That is why you are there, of course. Look at the next image:

Here too the background was a bit lighter. However, it was not that much brighter. I brightened it even more to pull you into the image. The tracks lead you to where they disappear. By lightening that part we now have two compositional elements working together to do the same thing thereby making its effect even stronger.

          When you process your images look at what is the most important and make sure that you lighten that part just a bit. Please be aware that when we lighten an image you loose some contrast. So always add contrast as you lighten. Conversely, darken sections to direct the viewer away from those areas. Have fun editing your images.