really it depends on what you want to make, because
there are lots of different things you can do with flash.
to make a good movie, you'd need to learn:
1. how to use all of the drawing tools, and practice making simple things.
2. basic actionscript, like a play button, a stop frame, etc.
3. how to create movieclips, buttons, graphics, and motion tweens.
4. and how to turn a brilliant idea into a brilliant flash.
if remember when i was a flash n00b i didn't know:
there are two filetypes for flash, .FLA and .SWF.
.FLA = the file you can edit, and change to make the movie.
.SWF = the movie itself, you cannot edit it.
after your finished with your .FLA, you need
to export your .SWF, and then upload to wherever.
[in your case, its going to be here at newgrounds]
hope something i said helped,
good luck :]
P.S. dont upload any crap to newgrounds, please and thank you in advanced.