I started out practicing on basic editing: Exposure, Contrast, highlights, shadows, colors, and brightness.
It's really simple. Anyhow, I'm assuming you know how to open a photo CS6.
Click on Images Tab > Adjustments. From there you can adjust all of the above mentioned basic edits. Now you can target specific individual areas such as the dog or the back ground wall by selecting the area with the Quick Select Tool. I use this when I JUST want to lighten up the foreground of a landscape photo for example. You just quick the Quick select tool and outline what you want selected. This can be a pain sometimes. Once selected, moves to edit the photo will only happen inside the selecting area. When you're finished, right click on control and click deselect (Mac user).