To start with, search out some information on photography composition. These are nothing but static snapshots of your dog, and as said, most have the dog cut off.
I've been playing out in the yard with my yellow Lab for the past couple of weeks trying to get a good photo of her in action. It's not easy. She is very fast. I've taken probably hundreds of photos now and nothing is good.
Once you read a bit and understand composition, try some stuff out on an easier subject. Flowers, landscapes, or something other than the dog. Like I said, I'm finding it quite difficult to use the dog as a photographic subject. With a static subject, you can explore the composition "rules" and frame your photos in different ways to see what works and what doesn't.
After learning about composition, start in on the different modes of the camera, aperture priority, shutter priority, and manual. From there, seek out info on aperture, shutter, and ISO and how they relate to one another to create the exposure.
You can see in your examples above how some shots the grass is way too bright while the dog is very dark. That's a result of using your camera in automatic mode. You need to understand metering the scene, which is when your camera is measuring the light and adjusting the exposure. In auto, the camera assumes and adjusts automatically. In the more manual modes (A, S, or M) you are in more control along with using some of the different metering modes.
Check out many topics on
Luminous Landscape or
Cambridge in Colour (just noticed now that it is "Colour" and not "Color") to get some great information. It takes a while to understand everything, but it is all quite simple once you do understand. It takes a lot more than just pointing a camera and pressing the shutter button.
Have fun. Lot's to read and learn, but it's quite satisfying when you get hooked on the photography stuff.