This question comes up often on this forum.
For the most part, you can't. You may be able to tweak the tone or filter certain frequencies using the various audio effects. But even professionals are often forced to re-record audio in movies when it was recorded with too much background or wind noise.
I agree with Steve. Because of the broad frequency range in wind noise, it can be tough, to impossible to correct.
However, this article will give you some tips, that might "improve" your Audio, to some degree: http://forums.adobe.com/message/2860521#2860521
I film outside every day. I bought a windsock from this company: http://www.thewindcutter.com/shop/
They were very helpful to me in getting something custom made for my iPhone, which has a tiny, tiny microphone.
The tiny, tiny windsock makes a significant difference in my videos!