It's a start...
Suggestions:
Your flash needs a preloader. On the Newgrounds Flash Portal page, there's a link right below the "Submit" button that says, "GET NG LOADERS N' STUFF!" Click that link to download a .FLA with a preloader in it. Copy and paste the first frame of that into your animation, and you'll have a preloader, complete with a start button.
Your file size was really large, most likely because you did not compress your sound. To learn how to optimize your audio, click the "LEARN FLASH" link below the "submit" button on the portal page, then click "audio optimization" -- it's near the top of the tutorials section.
Your audio should end at the end of your flash instead of continuing on forever. If you set your audio to "stream" and end the audio at the end of your flash, your file size will also be smaller. Your sound loops on top of itself now, which is really not good.
Your flash loops endlessly. You can add an actionscript stop(); code to the final frame of your flash to stop it from going on forever, or, better yet, add a replay button at the end. If you're unsure of how to do this, check the Newgrounds flash tutorials for help.
There was very little actual animation in this flash; it basically amounted to a slide show. Consider learning how to tween -- or, if you already know how, consider using tweens more.
This flash had no background, so the action took place in a vast void of nothingness. Think about adding backgrounds to your next flash.
Your flash didn't really tell a story or demonstrate any kind of meaning or purpose. While "random" can be good if done well, you might consider adding some kind of a plot or story line to your next flash.
Hope that helps. Good luck with your next flash!