I just uploaded my first movie that I made 11-12 years ago last night (The Rifle Range). I thought mine was great back in the day even know it looked pretty unfinished. I had sound though. Ha ha. I have been tinkering ever since. Then I found Newgrounds.com and was like ehhh. Mine Sucks ass. I still uploaded it though. I figured it would be cool to put my stuff out there finally.
Keep playing around, I am sure you will get better. Sounds are easy. You can drag and drop them from the library in Flash and you can upload them to the library from pretty much whatever you want. Give it another try. Can only get better!!