Editing Movie Brightness;

Hey all,
Now, I recorded some shit but now it seems it's way too dark,
And I was looking for software to edit the movie's brightness [Wich aparrently you can't do with windows movie maker].

So, I downloaded some stuff but I couldn't install it,

Anyhow, someone know's a program/method to do this [editing the movie itself, not editing it in windows media player, it's ment for youtube] ?

Thanx.

Crude Sapphire.