Hi @Sophia Sulla ,
File 7623 is underexposed, has a white balance issue (too cool), noisy and with color fringing. You could probably get a sharper focus. One thing that is sure is that the area of water in the forefront is out of focus.

File 7303 is out of focus, underexposed and noisy.

File 7219 is out of focus, noisy and underexposed.

With these example I think you should have a fair idea what to look for to avoid what cannot be corrected and to correct what you need to. Before uploading you file you need zoom in and to check them for issues as outlined on this page and the followup. Issues that you can correct use a photo editor such as Adobe Photoshop or Lightroom to correct those. Those that you cannot correct you'll just have to discard and to make sure you do not make the same mistake in the future.
Adobe has resources you can utilize to get get it right. You can first of all make sure you read-up the info of the link you get with your rejection reason. Learn the Contributor requirements and some tips with examples to get you files accepted.
Best wishes
Jacquelin