The image really should be sharp and full size (640 pixels in one dimension at least), it will help you quite a bit. It gives the impression that you are making it small to cover up some imperfection in the original image, and that's never a good idea.
This image is too small. Now look up, on the bar at the top of your page should be some headings that say things like "My Home" "Challenges" "Photos" and among them is one that says "Learn" click on learn and read the tutorial: Using Photoshop to Prepare Photos for DPC Challenges
A pretty small image and that is going to hurt you a lot here. Try to use the full 640px width to allow for best viewing. What I can see of the shot looks good, though.