Don't be bashful! If you want comments, give comments. You don't need to be an expert photographer to express your opinion about the work of others. You don't need to go into great depth. A simple remark about cropping, composition, color, subject matter, etc. can be of just as much help to a budding photographer as an in-depth critique.
Action shots can be tricky if you want to show a subject in motion as opposed to freezing a subject in action. Freezing an image is easier because you can set a quick shutter speed and snap away — catching people and things in mid-air. Showing somebody or something in motion is more complicated because you have to adjust your shutter speed to show motion without the entire picture looking blurry or too soft. Take a photo of someone or something in action and show movement. Your image can be an animal, an athlete, a car, or anything that moves. Post your best to the Web site and describe the lighting challenges you faced while taking the photo.