I have to disagree I'm affraid,
this is just friendly criticism by the way
the dog's face it dark, and his behind is lightened...just have him run the other way and take the shot again.
the other shots
, not a good composition, you can see the dog is doing something, but most of the times you miss out on essential stuff like his face.
However, you do know how to focus on an ( moving ) object. But in general I would give you the advise to keep the sun coming from behind you.
Anyway, just have fun with your camera