Pictures rejected

[anita_5946]

Hi everyone. These are some of the pictures i submitted that were rejected due to "quality problems". I can't understand what can i do better to get my next pictures aproved. i don't have any other camera and i was pretty happy with these first pictures. I would apreciate some feedback. thank you 

[yamato7]

I'm worried about underexposure and sensor dust.

The part that is in focus should be the main focus, but the horse's face is not in focus.
It's strange that the horse's face is not visible even though it is in focus.

DSC_0143

The foreground bokeh is too pronounced and the power lines in the background are distracting.

[RALPH_L]

photo 1: sensor spots and no commercial value.

photo 2: poorly cropped and the foreground is too blurry.

photo 3: underexposed and not sharp. 

[Nancy OShea]

What kind of camera?

Do you own a tripod?

Have you enrolled in any photography courses?

[Ricky336]

Hello,

The most obvious thing here is your composition—room for improvement.

Composition:
https://www.adobe.com/creativecloud/photography/discover/photo-composition.html