I think your problem may be that the file size you have uploaded is 15Kb, rather than 200 you are allowed! mark it down to experience, and remember to use the maximum resolution for your next entry.
Nice composition and looks like a good shot but you have used way too much compression when you have resized and saved, the photo can be 150kb and you have 15kb so maybe a mistype?
Try saving at 75% quality or 20% compression depending on what software you are using. Also, have a look under learn as you will find some useful info there
I'm commenting because I voted this pretty low. This looks like it might be one of your first entries and believe me I'm not far from my first. You will learn a lot from each challenge you enter. The focus is a bit soft. Maybe the autofocus wasn't working properly? I also think it's a bit overexposed. Again if the camera was set to 'Auto' this is not unusual. If you aren't using photoshop or some other photo editing program, I would suggest that you invest in whatever you can afford. Elements is a good and not too expensive program.
I can see good detail on the Sparrow's eye, but the shot feels quite soft overall and I'm seeing some odd pixellation around the bird's outline. Sharpening artifact, maybe? Composition is OK but I might have played with including the bird's shadow, if he held still for a few more pictures, just to add some more interest to the shot. And desaturated the blue tinge to the shadow.
Your subject is a good example of urban wildlife. It looks as though your focus is fine, but there are some strong compression artifacts which has resulted in a substantial loss of detail. There is also a strange fuziness around the sparrow, and strata in the sky - I suspect that you may benefit from reading the lesson on uploading images to DPC which can be found in the Tutorial section; if you need any further advice, drop me a PM.